DoJ&CD Outage Highlights Windows 11 KB5066835 Risks Across Localhost and WinRE

South Africa’s Department of Justice and Constitutional Development (DoJ&CD) has confirmed a widespread outage after a recent Windows 11 security rollup created a system-level fault that rendered multiple departmental services inoperable, with restoration work expected to continue for days or weeks as the department coordinates remediation with Microsoft engineers.

Background​

The problem traces to Microsoft’s October cumulative update for Windows 11, identified by vendor documentation and incident timelines as KB5066835, which began shipping in mid‑October and quickly attracted reports of two high‑impact regressions: a kernel‑mode HTTP stack (HTTP.sys) regression that broke localhost (127.0.0.1) HTTP/2 connections, and a separate fault that made USB keyboards and mice unresponsive inside the Windows Recovery Environment (WinRE).
Those regressions manifested across both developer workstations and production endpoints. In practice, applications and administrative consoles that depend on local loopback connections, as well as recovery flows essential to device repair, experienced abrupt failures—symptoms that quickly escalated into operational outages for organisations with heavily Windows‑centric estates, including the DoJ&CD.

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What Microsoft’s patch changed — the technical anatomy​

HTTP.sys, localhost and the HTTP/2 handshake​

At the centre of the outage is HTTP.sys, the kernel‑mode HTTP listener that Windows uses to accept and negotiate incoming HTTP traffic for IIS, IIS Express, and any process that registers URL prefixes with the kernel. The October rollup introduced changes that, in some configurations, mishandled HTTP/2 negotiation over the loopback interface, causing connections to be reset during the protocol handshake and preventing user‑mode servers from receiving requests. The visible client errors included ERR_CONNECTION_RESET and ERR_HTTP2_PROTOCOL_ERROR.
Why this matters: many modern apps (developer tooling, local admin panels, embedded web UIs inside desktop software and appliances) use loopback bindings (127.0.0.1 or ::1) for internal communications or local management. When the kernel listener resets those sessions before a user‑mode process can respond, the symptom looks like "the app is offline" even though the user process itself may be running fine. The result is broad functional collapse across disparate applications that share the same OS networking plumbing.

WinRE regression: recovery tools rendered unusable​

The second regression affected WinRE, a minimal "safe OS" used for offline diagnostics and repair. The October update replaced or altered Safe OS components on some machines in a way that prevented USB host controller or USB driver initialization within the recovery image. The practical consequence: USB keyboards and mice stopped working inside WinRE, blocking on‑device recovery workflows and leaving many systems effectively unrepairable without physical intervention or pre‑staged alternate recovery media. Microsoft acknowledged the problem and later shipped an out‑of‑band fix intended to restore WinRE input functionality.

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Timeline — how the incident unfolded​

• October 14, 2025 — Microsoft publishes the October cumulative update for Windows 11 (KB5066835).
• Mid‑October — Community reports and enterprise helpdesks begin reporting localhost loopback failures and WinRE input loss. Symptoms appear as HTTP/2 connection resets and unresponsive USB input in recovery.
• Microsoft posts known issues to its Release Health dashboard and starts triage; organisations report operational impacts.
• Microsoft deploys remediation channels: a Known Issue Rollback (KIR) for some HTTP.sys regressions and an out‑of‑band cumulative update (e.g., KB5070773) to address the WinRE USB input regression. Enterprises also received registry mitigation guidance to force HTTP/1.1 behavior for loopback connections as a temporary fix.
• October 22, 2025 — South Africa’s DoJ&CD issues a media statement confirming its operations were affected and that it is working with Microsoft engineers to restore services.

This sequence shows swift vendor recognition and active remediation — but also the reality that kernel‑level regressions propagate quickly and unevenly across diverse fleets, producing unpredictable business impact.

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Impact on Department of Justice operations — practical consequences​

When a justice department’s desktops, case‑management terminals, or local middleware rely on loopback services for authentication, document signing, or embedded administrative UIs, the failure of localhost connectivity can cascade into immediate service interruption. The reported operational impacts for DoJ&CD—based on the department’s media statement and incident summaries—include:

• Delays issuing court documents, warrants, and letters of authority.
• Disruption to electronic bail and remand processing.
• Temporary suspension or slowdown of online filing and case‑management interfaces.
• Impaired internal email gateways or identity callbacks where local services act as intermediaries.

The department’s public note did not enumerate a line‑by‑line inventory of affected systems, which is typical during an active incident; however, the combined technical and operational evidence indicates that these are not minor desktop glitches but interruptions to mission‑critical workflows that can ripple into both legal timelines and citizen access to justice.

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Microsoft’s response: KIR, out‑of‑band patches and guidance​

Microsoft moved quickly to acknowledge the regressions on its Release Health pages and used several remediation mechanisms:

• Known Issue Rollback (KIR): a server‑side rollback technique that reverses specific changes for many customers without requiring a full uninstall of the cumulative update. KIR is useful when the regression is tied to a single code change that can safely be reversed at scale.
• Out‑of‑band cumulative update (emergency patch): Microsoft issued an OOB update (reported in vendor timelines as KB5070773) to address the WinRE USB input regression and include other urgent fixes. This patch was distributed through Windows Update and Microsoft Update Catalog channels.
• Interim mitigations: Microsoft documented temporary workarounds—such as disabling HTTP/2 for loopback via registry keys to force HTTP/1.1—while advising administrators to apply vendor fixes or KIR where available. These mitigations carry trade‑offs and must be tested before enterprise deployment.

These steps reduced exposure for many organisations, but the rollout and verification process is inherently uneven across heterogeneous estates, so some customers experienced longer restoration timelines that required hands‑on remediation.

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Mitigation and remediation: recommended steps for IT teams​

For organizations currently affected or seeking to harden against similar incidents, the following prioritized checklist condenses practical, defensible actions:

• Inventory and triage
• Identify all Windows 11 and Windows Server endpoints running the 24H2/25H2 servicing branches and confirm whether KB5066835 (or later cumulative updates) is installed.
• Apply vendor fixes first
• Check Microsoft Release Health and apply Known Issue Rollback (KIR) or the designated out‑of‑band cumulative updates via your management channels (WSUS/Intune/SCCM) as soon as they are available. Prefer managed KIR packages over ad‑hoc uninstalls where possible.
• Use controlled mitigations where necessary
• If a KIR or OOB fix is unavailable, consider controlled, temporary mitigations such as disabling HTTP/2 for loopback (registry toggles EnableHttp2Tls = 0 and EnableHttp2Cleartext = 0 under HKLM\SYSTEM\CurrentControlSet\Services\HTTP\Parameters) in test rings first. Reboot and validate behavior before broader deployment. This is a stopgap and not a replacement for vendor patches.
• Restore recovery paths
• For WinRE issues, install Microsoft’s OOB fix immediately; where immediate patching isn’t possible, ensure alternative recovery media (bootable WinPE images with correct USB drivers) and secure access to BitLocker recovery keys.
• Validation and documentation
• After remediation, perform end‑to‑end tests on representative hardware (IIS sites, local developer tooling, vendor embedded UIs, and WinRE). Record actions, timestamps, and test results for audit and post‑incident analysis.

Warning: some community workarounds (e.g., manually replacing winre.wim images) have proven effective in labs but carry risk, especially for BitLocker‑protected machines; perform such interventions under formal change control and with backup keys accessible.

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Strengths shown and systemic weaknesses exposed​

What worked well​

• Rapid vendor action: Microsoft publicly acknowledged the regressions and deployed multiple remediation channels (KIR and an out‑of‑band cumulative update) faster than a traditional monthly cadence would allow. This accelerated restoration for many customers.
• Transparent public communication by DoJ&CD: The department’s quick public acknowledgement that the outage was vendor‑related helped manage stakeholder expectations and opened a direct remediation channel with Microsoft engineers.

What failed or is risky​

• Single‑vendor dependency: The incident underscores how a regression in a widely used platform component can create concentrated risk for public services that depend heavily on one OS vendor’s update pipeline. When a kernel driver regresses, the impact can cascade across unrelated apps.
• Inadequate canary testing against recovery flows: The WinRE regression demonstrates that recovery must be tested as a first‑class concern; an update that impairs recovery tools multiplies operational risk.
• Heterogeneous estate complexity: Large government estates with varied OEM drivers, EDR products, and custom integrations are more prone to edge‑case failures that escape vendor QA and cause uneven remediation timelines.

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Broader policy implications for government IT​

This outage is more than a technical incident; it is a governance exercise in platform risk management. Public‑sector IT leaders should convert the immediate lessons into institutional changes:

• Mandate staged canary rings and test matrices that explicitly include WinRE/Safe OS assets, local loopback scenarios, and common vendor management consoles.
• Build contractual SLAs with major platform vendors that specify emergency remediation timelines and engineer escalation routes for kernel‑level regressions.
• Maintain resilient manual or analog fallback procedures for essential public services (paper workflows, delegated manual sign‑off processes) that can be activated for the narrow set of functions that cannot tolerate downtime without legal or constitutional consequences. The DoJ&CD’s media note rightly flags restoration will take days to weeks—agencies must plan for that contingency.

Longer term, governments must weigh diversification strategies (redundant platforms, hardened images, or isolated air‑gapped recovery appliances) to reduce the chance that a single platform regression paralyzes core civic functions.

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What remains uncertain — claims requiring caution​

Public reporting and vendor notes provide a clear technical arc, but several specifics remain unverified in public disclosures:

• Precise inventory counts of affected DoJ&CD endpoints and which exact subsystems (case management, email gateways, document signing) were knocked offline were not published in the department’s statement. That level of detail is typically internal during active remediation and will be necessary for a formal post‑incident assessment. Treat any numeric estimates as provisional.
• The definitive line‑by‑line root cause analysis at the binary level (for example, a single HTTP.sys subcomponent change) has not been published by Microsoft; community analyses converge on HTTP.sys and WinRE driver changes, but a full, public post‑mortem naming code paths and fixes will be required for forensic closure.

Flagged claim: community anecdotes that certain Defender intelligence updates or specific driver toggles restored functionality on a subset of machines are interesting but not universally reproducible; treat these as exploratory, not guaranteed remediation steps.

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Takeaways for IT leaders and administrators​

• Treat OS updates as major change events, not routine housekeeping. Build patch windows that allow for representative‑hardware validation and an explicit recovery‑path exercise.
• Preserve and rehearse alternative recovery options (bootable media, offline images, PS/2 fallbacks) and ensure BitLocker keys are accessible during incidents.
• Prefer vendor‑sanctioned rollback mechanisms (KIR) and out‑of‑band fixes over broad uninstall strategies when possible; test these in canary rings before wide deployment.
• Maintain clear incident playbooks including communications templates for stakeholders and statutory authorities—justice systems have deadlines and legal processes that need explicit handling when digital systems go offline.

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Conclusion​

The DoJ&CD outage is a high‑visibility example of how platform regressions at the kernel level can convert a routine security update into a multi‑day operational crisis for public services. Microsoft’s rapid remediation actions—public acknowledgement, Known Issue Rollback, and an out‑of‑band patch—substantially reduced harm for many customers, but the incident spotlights enduring fragilities in vendor dependency, recovery validation, and patch‑management discipline for mission‑critical estates. Governments and enterprises must treat recovery and loopback scenarios as first‑class test cases, build robust canary rings, and negotiate stronger remediation commitments with major platform vendors to prevent a single update from taking courtrooms, case‑management systems, and other essential public services offline in the future.

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Source: IOL Justice and Constitutional Development services offline due to Windows system error

 

[ChatGPT]

South Africa’s Department of Justice and Constitutional Development (DoJ&CD) says a Windows 11 system error tied to a recent Microsoft patch forced multiple departmental services offline, and restoration work with Microsoft engineers will continue over the coming days and weeks.

Background​

The disruption traces to Microsoft’s mid‑October cumulative update for Windows 11 (identified in community reporting and vendor logs as KB5066835), which community and vendor telemetry linked to two high‑impact regressions: a kernel‑mode HTTP stack (HTTP.sys) regression that broke loopback (localhost, 127.0.0.1) HTTP/2 connections, and an unrelated Safe OS regression that rendered USB keyboards and mice unresponsive inside the Windows Recovery Environment (WinRE). Microsoft documented the WinRE symptom and released an out‑of‑band cumulative update (KB5070773) to restore WinRE USB input; Microsoft and community channels also described a server‑side Known Issue Rollback (KIR) or other mitigations for the localhost/HTTP.sys regression.
This combination of failures—one at the kernel networking layer and the other in the recovery image—created practical consequences for organisations that rely on Windows‑bound local services and recovery tooling, including government departments whose day‑to‑day workflows depend on local web endpoints and automated recovery procedures. The DoJ&CD’s public statement confirmed operational impacts and noted Microsoft engagement while flagging that full restoration could take days or weeks.

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What broke — the technical anatomy​

HTTP.sys, localhost and the HTTP/2 handshake​

At the center of the localhost failures is HTTP.sys, the kernel‑mode HTTP listener that Windows uses to accept and negotiate incoming HTTP traffic for IIS, HttpListener‑based apps, and any user‑mode process that registers URL prefixes with the kernel. When HTTP.sys handles protocol negotiation or TLS frames incorrectly, it can terminate a session before the user‑mode server ever receives a request — producing immediate connection resets and HTTP/2 protocol errors such as ERR_CONNECTION_RESET and ERR_HTTP2_PROTOCOL_ERROR. That symptom set was widely reported after KB5066835 and was mapped by community analysis to changes affecting HTTP/2 loopback negotiation or TLS handling on the loopback interface.
Why that matters in practice: many desktop and server applications embed lightweight local web servers or rely on loopback endpoints for UI, authentication callbacks, inter‑process messaging, or management consoles. When the kernel closes those sessions early, the visible symptom looks like “the app is offline” even when the application process is still running. For organisations with heavily Windows‑centric estates, the effect can cascade rapidly across disparate systems that share the same kernel plumbing.

WinRE: the recovery image that stopped accepting USB input​

Separately, the October update altered Safe OS/WinRE components used for offline diagnostics and repair. WinRE runs a minimal kernel and driver stack; if the Safe OS image is updated with an incompatible or incomplete set of USB host controller drivers, USB keyboards and mice will not initialise inside the recovery UI while continuing to work inside the full Windows desktop. That symptom renders local recovery options (Startup Repair, Reset this PC, etc.) effectively unusable on affected systems that rely on USB input. Microsoft acknowledged the WinRE USB input failure and issued an out‑of‑band cumulative update — KB5070773 — specifically listing the USB symptom among its fixes.

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Timeline: how the incident unfolded​

• October 14, 2025 — Microsoft ships the October cumulative update for Windows 11 (community identified as KB5066835).
• Mid‑October — Community reports surface of localhost (loopback) failures and WinRE USB input loss; enterprises and developers report ERR_HTTP2_PROTOCOL_ERROR and failed local admin UIs. Microsoft adds Known Issues to Release Health for affected builds.
• October 20, 2025 — Microsoft releases an out‑of‑band cumulative update, KB5070773, which includes the WinRE USB input fix and aggregates the October LCU. Administrators are urged to install the OOB update to restore recovery functionality where affected.
• Following days — Microsoft deploys KIR and targeted mitigations for the HTTP.sys regression while organisations coordinate rollbacks, registry mitigations, and testing to restore local services. Several public‑sector organisations, including South Africa’s DoJ&CD, reported operational impacts and engaged Microsoft engineering.

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The DoJ&CD outage: operational impact and real‑world consequences​

The DoJ&CD described the outage as caused by a “global Windows 11 system error” following a Microsoft patch rollout and said restoration work will continue over days or weeks. That public acknowledgement is important: when a national justice department’s case‑management and document‑issuance platforms are interrupted, the impact can be immediate and legally sensitive. Reported operational consequences in similar incidents include:

• Delays in issuing court orders, warrants and legal notices.
• Interrupted electronic filing and case‑management workflows.
• Disruption to bail and remand processing tools that integrate local middleware or use local signing endpoints.
• Reduced ability to use on‑device recovery tools, increasing the need for physical intervention on endpoints.

It is essential to be precise: the DoJ&CD statement did not enumerate the full list of affected systems, nor did it quantify how many endpoints or which specific services were down. That granular inventory is typically produced only after internal triage and vendor forensics; as such, any public figure about scope should be treated as provisional until the department or vendor publishes a detailed post‑incident summary.

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What Microsoft did: KIR, OOB patch and guidance​

Microsoft employed multiple remediation mechanisms:

• Known Issue Rollback (KIR): where possible, Microsoft used server‑side rollback tooling to reverse specific registry‑level or code changes without requiring a full uninstall of the cumulative update. KIR can propagate via Windows Update channels to many devices automatically. Community reporting indicates KIR helped some environments recover localhost connectivity quickly.
• Out‑of‑band cumulative update (KB5070773): Microsoft published KB5070773 on October 20, 2025. The KB explicitly lists the WinRE USB symptom and is cumulative, including the October LCU plus the WinRE remediation. Administrators were advised to install this patch via Windows Update or the Microsoft Update Catalog.
• Interim mitigations: While waiting for vendor fixes or KIR propagation, IT teams used temporary workarounds such as disabling HTTP/2 for loopback, installing targeted driver or Defender intelligence updates that reportedly resolved some cases, or, where change control allowed, uninstalling the cumulative update as a short‑term rollback. These mitigations carry trade‑offs and must be tested before enterprise deployment.

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Practical technical mitigations (for sysadmins)​

The following steps summarise pragmatic actions IT teams should consider when addressing the HTTP.sys/WinRE regression cluster. These are operational recommendations — test in a lab ring and follow change control.

• Inventory and prioritise
• Identify Windows 11 devices on servicing branches 24H2 and 25H2 and prioritize endpoints that host local services or provide critical recovery paths.
• Apply vendor fixes first
• Install KB5070773 immediately on systems that show WinRE USB input failure to restore recovery functionality. Use the Microsoft Update Catalog or Windows Update for Business channels where possible.
• Use Known Issue Rollback (KIR) where available
• Confirm KIR propagation in your tenant. Where KIR has been applied by Microsoft, follow verification steps and reboot as required.
• Temporary registry mitigation (test carefully)
• Some IT teams reported success forcing HTTP/1.1 for loopback by creating or editing registry values. Two registry paths circulated in community guidance; implement only after validating in a test environment:
• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP\Parameters — create DWORDs such as EnableHttp2Tls = 0 and EnableHttp2Cleartext = 0 to disable HTTP/2 system‑wide for HTTP.sys loopback negotiation.
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\IIS\Parameters — older guidance suggests entries under IIS Parameters to adjust HTTP/2 behavior for IIS scenarios. Validate which key affects your workload.
• After registry edits, restart the HTTP service or schedule a host reboot. Document the change and be ready to reverse it.
• Rollbacks when necessary (use caution)
• If immediate service continuity requires it and change control permits, uninstall KB5066835 using wusa.exe (for example: wusa /uninstall /kb:5066835) and reboot. Uninstalling an LCU has security implications and should only be done when compensating controls exist.
• Validate WinRE and recovery media
• Create and validate external recovery media and ensure BitLocker keys and recovery images are accessible. On a small set of representative devices, boot to WinRE and confirm USB input is functional after remediation.
• Post‑repair verification
• Test developer workflows, Visual Studio/IIS debugging, embedded appliance web consoles, and vendor admin UIs to confirm local loopback connectivity is restored. Keep records of timestamps, actions and test evidence for audit and after‑action review.

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Analysis: what this incident reveals about modern patching risk​

Strengths observed​

• Vendor responsiveness: Microsoft acknowledged the issues on Release Health, deployed KIR and released an urgent out‑of‑band patch (KB5070773) rather than waiting for the next monthly cycle, which is appropriate for a regression that rendered recovery tooling unusable.
• Rapid community triage: Developer and admin communities quickly identified patterns, shared reproducible symptoms and practical mitigations; that community telemetry accelerated vendor focus.

Structural weaknesses and risks​

• Kernel‑level shared surface: When a change touches kernel‑mode components such as HTTP.sys, the surface area of impact is large and diverse. Localhost services used by disparate applications are suddenly exposed to a single point of failure. The result: many seemingly unrelated services fail at once.
• Safe OS sensitivity: WinRE’s minimal driver stack increases fragility: Safe OS updates that don’t carry the exact driver set needed by varied OEM hardware can break recovery tools. That elevates MTTR because automated offline repair becomes impossible without physical intervention or alternative recovery media.
• Staging and canary gaps in critical estates: Public‑sector organisations and large enterprises that lack sufficiently deep canary rings or long‑lived test images risk exposure to update regressions. A patch that passes fresh‑image tests may still regresses on upgrade paths or long‑lived devices.
• Operational and legal exposure: Justice systems operate under statutory timelines; outages that delay filings or court orders can produce legal consequences and reputational harm. The inability to quickly enumerate affected systems in public reporting also complicates stakeholder communication.

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Recommendations for public‑sector IT leaders​

• Maintain robust, tested recovery images and offline recovery media for all critical endpoints; validate WinRE inputs on representative hardware after each patch cycle.
• Implement conservative canary rings that include long‑lived upgrade paths and common vendor agents (EDR, management clients) rather than relying solely on fresh‑image tests. Exercise patience in broad rollouts for mission‑critical endpoints until the canary ring has proven stability.
• Negotiate vendor SLAs and direct engineering escalation channels with platform suppliers to secure priority remediation windows for regressions that threaten public services. Document escalation flows and communications templates for public notifications.
• Harden alternatives for mission‑critical functions: preserve manual or analog pathways for essential legal processes that can be activated if electronic systems are unavailable. Maintain auditable logs of fallback activations and remediation.
• Balance security and availability: where feasible, apply security LCUs to internet‑facing servers while staging developer/management workstations differently, and ensure rollback plans are ready and tested.

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Things we still cannot verify and cautionary notes​

• The DoJ&CD’s public note did not list the exact systems that were down nor provide a machine count or precise timeline for restoration; that inventory remains internal and unconfirmed in public channels. Any specific claim about the number of affected devices or exact service lists should be treated as unverified until the department or vendor publishes a post‑incident report.
• Community workarounds that involve swapping WinRE images, replacing winre.wim, or manual driver manipulations have been effective in lab contexts but carry operational and security risk (BitLocker key access, driver signing, OEM support). These steps should only be executed by experienced teams under change control.
• Reports that Defender intelligence updates alone fixed some machines appear in community threads but are not universally reproducible; treat such claims as exploratory and test them in a controlled environment before operational reliance.

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A sober takeaway for Windows shops​

This incident is a concentrated example of a broader reality: modern operating‑system updates touch many deep and widely reused subsystems. When a regression lands in a kernel‑mode component or Safe OS payload, the fallout can be disproportionate — affecting developer tooling, vendor appliances, administrative consoles, and the recovery mechanisms organisations depend on.
Microsoft’s rapid use of KIR and an out‑of‑band update demonstrates that vendor remediation channels work when an issue is severe. Still, the episode should prompt a quiet but urgent reassessment in public and private sector IT: build canary rings that mirror real‑world upgrade history, prioritise verified recovery media and contingency processes, and ensure contractual and engineering channels exist with platform vendors for high‑severity regressions.

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Quick checklist — what to do now (concise)​

• Confirm whether KB5066835, KB5065789 (September preview) or related updates are installed across your estate.
• If WinRE input is broken, deploy KB5070773 immediately and validate recovery.
• For loopback/localhost failures, check KIR status and consider registry mitigations in a test ring before broad rollout.
• If necessary for business continuity and after risk assessment, perform controlled uninstalls of the offending LCU and block reinstallation until fixes are validated.
• Create/validate bootable recovery media, secure BitLocker keys, and document fallbacks for essential judicial functions.

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The DoJ&CD outage underscores a difficult truth for IT leaders: platform stability is not only a technical attribute but a policy challenge that touches legal timetables, public trust and service continuity. The immediate imperative is pragmatic remediation and careful verification; the longer‑term imperative is structural: better canary testing, safer Safe OS update controls, and operational playbooks that anticipate vendor regressions before they become agency crises.

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Source: capetimes.co.za Justice and Constitutional Development services offline due to Windows system error