Windows 11 August 12, 2025 — KB5063878 (24H2) & KB5063875 (22H2 / 23H2)
An in‑depth Breakdown for WindowsForum.com (Markdown)Short version (TL;DR)
- Microsoft released the August 12, 2025 Patch Tuesday cumulative updates for Windows 11. The 24H2 servicing branch is updated as KB5063878 (OS Build 26100.4946) and the 22H2/23H2 servicing branches are updated as KB5063875 (OS Build 22621.5768 / 22631.5768). ed packages that include a Servicing Stack Update (SSU) plus the Latest Cumulative Update (LCU). Expect the usual security hardening, quality fixes and a handful of AI/Copilot-related reliability updates.
- Admin guidance: test in a controlled Ukages are combined), and stage via WSUS/Intune if you manage fleets. Rollout is staged; follow Windows Release Health for known‑issue updates.
Table of contents
- Summary and release context
- What KB5063878 (24H2) contai22H2 / 23H2) contains
- Security and CVE highlights (what to watch for)
- Known or likely side effects and compatibility notes
- How to get and install the updates (consumer & enterprise)
- Recommended rollout strategy and checklist for admins
- Post‑update troubleshooting & rollback pointers
- Wrap‑up and links to discussion threads
Summary and release context
Microsoft’s August 2025 Patch Tuesday (released August 12, 2025) brings the monthly LCU (Latest Cumulative Update) and, where applicable, an updated servicing stack. The 24H2 release is packaged as KB5063878 and advances devices to OS Build 26100.4946; devices on the 22H2/23H2 branches receive KB5063875 and are advanced to build 22621.5768 / 22631.5768. These are delivered as combined SSU+LCU packages to ensure servicing stack readiness ahead of the cumulative changes.
Why this matters right now
- Monthly Patch Tuesday updates remain the primary distribution vehicle for nying critical patches exposes devices to known CVEs. The August releases continue Microsoft’s cadence of bundling servicing stack updates and cumulative fixes to minimize the number of reboots and sequencing errors during mass deployment.
- These releases also include fixes tied to Copilot/Copilot+ reliability and some Secure Boot certificate/cert rollover preparations (see details pilot-enabled workflows or manage Secure Boot across heterogeneous hardware, you’ll want to review the specifics before broad rollout.
What’s in KB5063878 (Windows 11, version 24H2)
Headline items
- Combined SSU + LCU for Windows 11 24H2 (packaged as KB5063878), moving 24H2 devices to OS Build 26 ck hardening and the usual collection of quality and security fixes.
- Fixes targeting Copilot/Copilot+ reliability and a handful of AI integration edge cases (improved restart/reliability after Copilot invocation, stability improvements for Copilot-related components).
- Preecure Boot certificate rollovers and related validation code paths — intended to make systems resilient to future certificate expiry/transition events. This is framed as “Secure Boot readiness” and should boot-time validation errors during upcoming certificate rollovers.
- Gaming and performance tweaks reported for scenarios where prior updates caused regressions for certain titles or GPU driver interactions. Community reporting indicates some performance polish in this releasend taskbar stability fixes carried over from previous months and refined for edge cases (tab duplication, explorer crashes, resizing issues).
- Delivered as a combined Servicing Stack Update plus Latest Cumulative Update (SSU+LCU). kaged, installation ordering complexities are reduced, but systems may still require a reboot to finalize servicing.
What’s in KB5063875 (Windows 11 servicH2 / 23H2)
Headline items
- KB5063875 is the August 12, 2025 cumulative update for Windows 11 servicing branches that use OS builds 22621 and 22631 (builds update to 22621.5768 / 22631.5768). Like the 24H2 package, it is shipped as a combined SSU+LCU so dliably.
- The release contains parity fixes for Copilot reliability found in the 24H2 build and a range of quality/security patches aligned to this servicing branch.
- Fixes for local privilege escalation and use‑after‑free scenarios that were identified in components (some of which are documented in for August). These are the typical vulnerability resolutions you expect on Patch Tuesday; review your telemetry for any affected services.
Security highlights (what admins and power users should watch)
- The August releases include fixes for several kernelbilities disclosed in Microsoft’s security guidance for this month. Community summaries and update catalogs for August list the usual mix of information disclosure, privilege elevation, and denial‑of‑service fixes. Apply the patches per your organization’s patfic CVEs discussed in community posts around August include issues in AFD.sys and RRAS components; these were flagged as high-priority to address for hosts that expose these services. If you run VPN gateways, RRAS, or services that expose legacy networking stacks, prioritize testing these updates in a lab before general deployment.
Known issues and compatibility notes (things reported / to watch)
- Staged rollout: Microsoft continues staggered/controlled rollouts; you may not see the update immediately via Windows Update depending on your device’s device‑based rollout eligiates to become available gradually.
- Secure Boot certificate prep: while this work is meant to be preparatory and harmless, environments with custom Secure Boot chains (OEM custom keys, certain managed HSM chains) should validate in a test ring before broad rollout to avoid unexpected validation failures during firmware interactions.
- Third‑party driver regressions: a small set of previous cumulative updates have historically produced isolated driver issues with older third‑party drivers. The s to test on representative hardware and ensure critical drivers are at vendor‑supported versions before mass deployment.
- Check Windows Release Health for Microsoft’s official known issues and mitigations. Community threads on WindowsForum will also collect earal workarounds if Microsoft hasn’t yet published KB notes.
How to get and install (consumer and enterprise)
Consumer / small business (Windows Update)
- Settings → Windows Update → Check for updates. The cumulative will appear as the August 12, 2025 update (KB5063878 for 24H2; KB5063875 for other bra are combined SSU+LCU packages, Windows Update will handle sequencing automatically in most consumer scenarios.
- For administrators or machines that require offline packages, the Microsoft Update Cataes the SSU and LCU MSU/MSIX packages for manual download (or combined packages). For advanced users, Microsoft’s catalog and the usual DISM / Add‑Package approach remain an option; community installation examples for prior updates use commands such as:
DISM /Online /Add-Package /PackagePath:C:\packages\Windows11.0-KBxxxxxx-x64.msu
(Replace the package path with the correct MEnterprise deployment (WSUS / Intune / ConfigMgr) - Import the update into WSUS or use Intune/ConfigMgr to approve and stage installs. Test in a pilot ring, then widen deployment once telemetry is clean. Because the package is a combined SSU+LCU, treat the package as a single deployment unit when approving.
- If the update you plan to deploy includes an SSU component that is not combined into the LCU, always install the SSU first and reboot before applying the LCU; however, for these August packages Microsoft bundled SSU+LCU where inis. Still, validate the package details prior to mass deployment.
Recommended rollout strategy & checklist for admins
- Read the release notes and any security advisories for August 12, 2025. Confirm CVEs relevant to your environment.
- Test in a small pilot group across representative hardware (Int OEM firmware builds). Pay special attention to firmware/driver interactions and Secure Boot flows.
- Confirm backups and rollback plans: create a system image or verified backup before broad deployment. If using SCCM/ConfigMgr, ensure your deployment is set to phased rings with automatic rollback if critical errors exceed thresholds.
- Check drs (graphics, storage, networking) for updates that may be required to maintain compatibility post‑patching.
- Stagger the rollout, monitor telemetry, and watch Windows Relergent known issues; adjust your pace based on real‑world telemetry.
Post‑update troubleshooting and rollback pointers
- If a device becomes unstable after installing the cumulative upndows Recovery → Uninstall Updates → choose to uninstall the latest quality update. This will revert the LCU (but not necessarily an SSU if applied separately).
- If you must fully revert, use a system image or reimage from known good meelated regressions: roll back the device driver via Device Manager to the prior version, or boot to Safe Mode and uninstall the problematic drissues to Microsoft via the Feedback Hub and track the device on Windows Release Health and vendor advisories. Community discussion threads on WindowsForum wilround steps while vendor/Microsoft fixes are prepared.
Community reaction & discussion (where to follow)
- WindowsForum threads have already been created summarizing the August 12 packages and collecting user reports for both KB5063878 and KB5063875. These threads will be the fastest place for peer troubleshooting and early‑adopter posts; search or follow the threads titled “KB5063878 (Aug 2025): Windows 11 24H2 SSU+LCU and Secure Boot Rollovers” and “Windows 11 Aug 2025 KB5063875: LCU+SSU for 22621/22631 with Copilot fix.”
Wrap‑up and recommended actions (concise)
- Home users: install via Windows Update when convenient; the combined SSU+LCU should be handled automatically. If you use custom Secure Boot keys or third‑party boot managers, test first.
- Power users and admins:ring, verify backups, confirm key drivers’ compatibility, and stage using WSUS/Intune. Prioritize devices that face the internet or run RRAS/AFD services for early patching if those CVEs apply to you.
- Keep an eye on Windows Release Health and the WindowsForum threads for practical reports and workarounds as the rollout proceeds.
Further reading & discussion (WindowsForum)
- KB5063878 (24H2) initial thread and discussion.
- KB5063875 (22H2/23H2) deployment notes 5 Patch Tuesday roundup and guidance for enterprise rollout.
- I can convert this into a ready‑to‑post WindowsForum thread (title, short summary, tags, and the full body), or
- Produce a short “what to do right now” checkliso your helpdesk or IT ops team, tailored for home users, SMBs, or enterprise fleets.
Source: Neowin Windows 11 (KB5063878, KB5063875) August 2025 Patch Tuesday out
