Microsoft’s September Patch Tuesday delivered a broad, operationally important set of security updates on September 9, 2025, covering Windows, Microsoft Office, SQL Server and related platform components — with industry trackers reporting roughly 80–86 CVEs patched and several high‑priority issues that merit immediate triage. (support.microsoft.com) (securityweek.com)
Patch Tuesday is Microsoft’s monthly security-release cadence, scheduled for the second Tuesday of each month. The September release followed the usual pattern of combined servicing‑stack updates (SSU) and Latest Cumulative Updates (LCU) for Windows client and server branches, alongside product‑specific advisories and KBs for Office, SQL Server and other server components. Administrators should treat the Microsoft Support and MSRC pages as the authoritative references for KB ↔ CVE mappings and installation guidance. (support.microsoft.com)
Important operational note: counts are shorthand. Your priority should not be the exact headline number but the exposure and impact of the individual CVEs that affect your estate. Map CVEs to asset inventory and prioritize internet‑facing systems, domain controllers, hypervisors and file‑handling services.
Flagged caution: any single outlet’s high‑level summary (including ours here) can be incomplete. Always verify the CVE list and vendor exploitability assessments against Microsoft’s Security Update Guide and the publisher KBs before finalizing your remediation plan. (support.microsoft.com)
Operational guidance in one line: inventory, snapshot, pilot, validate, then stage — with highest immediacy for internet‑facing RCEs, domain controllers, and hypervisors. Use Microsoft’s official KBs and the Security Update Guide as the single source of truth for CVE ↔ KB mapping and exploitability guidance before making deployment decisions. (support.microsoft.com)
Conclusion: the September release strengthens platform security substantially, but it requires disciplined execution and careful compatibility testing. Treat the vendor advisories and readiness infographics as operational planning tools, not a substitute for inventory‑based risk triage and validated pilot deployments. (support.microsoft.com)
Source: Computerworld For September, Patch Tuesday means fixes for Windows, Office and SQL Server
Patch Tuesday is Microsoft’s monthly security-release cadence, scheduled for the second Tuesday of each month. The September release followed the usual pattern of combined servicing‑stack updates (SSU) and Latest Cumulative Updates (LCU) for Windows client and server branches, alongside product‑specific advisories and KBs for Office, SQL Server and other server components. Administrators should treat the Microsoft Support and MSRC pages as the authoritative references for KB ↔ CVE mappings and installation guidance. (support.microsoft.com)Why this month matters
September’s cycle was distinctive for two operational reasons. First, headline counts reported by vendors vary — outlets cite numbers in the low‑80s up to the mid‑80s — because some trackers include cloud‑only, Xbox, Edge or third‑party fixes while others count only the on‑Windows CVEs. Second, the slate mixes traditional memory‑safety remote code execution (RCE) issues with a large number of elevation‑of‑privilege (EoP) flaws and operational hardening controls (for example, SMB auditing and enforcement options) that change how administrators should prepare and test before rolling enforcement into production. (secpod.com)What Microsoft published (high level)
Microsoft packaged September 9, 2025 updates as cumulative rollups plus discrete security advisories for platform components. The client and server cumulative KB for Windows 11 and Windows 10 were published alongside multiple product KBs (for .NET, Office, SQL Server, etc.), and Microsoft also made hotpatch options available for specific server SKUs where supported. These are not optional maintenance notes — they reflect precise combinations of servicing stack and platform fixes that have installation ordering and rollback implications. (support.microsoft.com)The authoritative playbook: consult MSRC and product KBs first
- Use Microsoft’s Security Update Guide and the individual Support KBs (the Windows cumulative KBs and per‑product KB pages) to map CVEs to the exact OS builds and product versions in your inventory.
- Treat vendor counts from third‑party trackers as useful signals but always validate CVE ↔ KB mappings against Microsoft’s published pages before mass deployment. (support.microsoft.com)
Headline vulnerabilities and technical highlights
Across reporters and vendor advisories, several vulnerabilities stood out as operational priorities for IT teams. Below are the most significant technical items and what they mean for administrators.SMB / NTLM hardening and CVE‑2025‑55234
One of the most widely emphasized advisories concerned an SMB server weakness that Microsoft addressed with both a code fix and audit‑first enforcement tooling. The update adds audit events and configuration toggles that let shops discover SMB endpoints that lack signing or Extended Protection for Authentication (EPA) before flipping on strict enforcement. Because relay‑style attacks and improper authentication handling can enable privilege escalation in misconfigured environments, this item is high priority for systems exposed to shared files, network backups, or legacy storage appliances. (secpod.com)High Performance Compute (HPC) Pack RCE (CVE‑2025‑55232)
A critical remote code execution flaw in Microsoft’s High Performance Compute Pack received elevated attention for both its high CVSS base score and the fact that clusters often expose management ports (notably TCP/5999). Microsoft flagged this as high impact and recommended that affected clusters be isolated behind firewalls and patched promptly. Blocking or filtering the HPC management port in front of clusters and treating HPC nodes as a high‑risk workload is prudent until your test deployments validate the update. (securityweek.com)Office document parsing and preview‑pane RCEs
This month included Office family fixes that historically lower the exploitation bar because they can be triggered by preview panes or thumbnail rendering (Explorer/Outlook). One notable RCE patched in Office was tracked as CVE‑2025‑54910 (heap overflow triggered by crafted documents). For high‑risk groups (mail servers, shared desktops, VDI pools) consider disabling preview panes or hardening mail gateways until the Office updates are applied and validated. (cybersecuritynews.com)SQL Server and third‑party libraries (Newtonsoft.Json)
Microsoft also patched instances where older versions of the widely used Newtonsoft.Json library were bundled in server components, closing denial‑of‑service (StackOverflow) vectors. Administrators running SQL Server and other server components that deserialize untrusted JSON should confirm library versions (upgrade to Newtonsoft.Json 13.0.1+ where applicable) and apply vendor KBs that specifically address embedded third‑party dependencies. (bleepingcomputer.com)Other high‑value items
- NTFS-related RCEs and kernel/driver privilege escalation vulnerabilities were fixed and deserve prioritization where hosts process untrusted file systems or network shares. (securityweek.com)
- Hyper‑V and virtualization components received fixes; hypervisors and hosts should be patched early in the rollout if they host multi‑tenant or business‑critical workloads. (securityweek.com)
The numbers: why counts vary and what matters
Industry trackers reported varying totals for the September release: numbers range from roughly 80–86 CVEs patched depending on what each outlet counts (cloud‑only fixes, separate Edge/Chromium advisories, Xbox and Mariner fixes, or non‑Microsoft third‑party CVEs included). SecurityWeek and Intrucept reported 86 fixes; BleepingComputer and SecPod, along with several vendor blogs, reported 81; others present slightly different tallies. That divergence is normal for complex Patch Tuesday cycles and is not itself an indication of error — it’s an artifact of differing inclusion rules. (securityweek.com)Important operational note: counts are shorthand. Your priority should not be the exact headline number but the exposure and impact of the individual CVEs that affect your estate. Map CVEs to asset inventory and prioritize internet‑facing systems, domain controllers, hypervisors and file‑handling services.
Conflicting claims about zero‑days — a caution
Some published summaries — including one interpretation seen in the Computerworld feed — suggested a lower‑urgency posture this month and characterized browser‑platform fixes as moderate in severity. That same Computerworld note implied there were “no zero‑days” and that Readiness did not recommend an immediate “patch now” posture. However, multiple independent trackers and vendor writeups reported one or two publicly disclosed zero‑day issues this cycle (notably the SMB advisory and the Newtonsoft.Json/SQL Server issue), and several outlets published prioritized triage advice for those items. Because these claims conflict, organizations should treat the zero‑day question conservatively: assume there are publicly disclosed, high‑priority issues and validate Microsoft’s MSRC bulletin for the official exploitability and patch guidance. (secpod.com)Flagged caution: any single outlet’s high‑level summary (including ours here) can be incomplete. Always verify the CVE list and vendor exploitability assessments against Microsoft’s Security Update Guide and the publisher KBs before finalizing your remediation plan. (support.microsoft.com)
Readiness team guidance and the infographic narrative
Multiple community posts and enterprise readiness syndicates published testing recommendations and infographics to help administrators triage the cycle. The recurring guidance is consistent:- Inventory first — identify internet‑facing servers, domain controllers, HPC clusters, SQL instances and Office‑heavy endpoints.
- Backup and snapshot critical systems, especially before applying combined SSU+LCU packages, which complicate rollback.
- Pilot updates in a representative ring, validate authentication flows (Kerberos, NTLM, service accounts), and test app compatibility (OLE DB, third‑party drivers) before broad deployment. (tenablecloud.cn)
Testing and deployment checklist (practical, prioritized steps)
- Inventory and risk triage
- Identify internet‑facing endpoints, domain controllers, hypervisors, HPC clusters, SQL Server instances and mail/VDI hosts.
- Backups and recovery
- Snapshot VMs and export critical application states. Test your restore process for at least one pilot server.
- Pilot ring
- Deploy to a representative pilot cohort (including a domain controller if possible in an isolated test domain) and monitor for 24–72 hours.
- Application compatibility
- Validate OLE DB and Newtonsoft.Json updates for SQL Server‑backed apps; check vendor advisories.
- Hardening telemetry
- Enable SMB audit events to discover legacy clients before turning on enforcement; use audit data to remediate incompatible devices. (secpod.com)
- Staged rollout
- Expand to targeted server classes (domain controllers, internet‑facing services) before full endpoint distribution.
- Mitigations when immediate patching is impossible
- Temporarily disable Office/Explorer preview panes, block or filter TCP/5999 for HPC management interfaces, enable SMB signing/EPA where feasible, and tighten firewall exposure for SQL endpoints. (splashtop.com)
Detection and compensating controls
- Ingest Microsoft’s new SMB audit events into SIEM (the advisory includes suggested event IDs and why to look for them).
- Update IDS/IPS and endpoint detection rules as vendors (Cisco Talos, Snort, and others) publish signatures for the most probable exploitation vectors for this cycle.
- For SQL Server and apps that embed Newtonsoft.Json, apply rate‑limiting and input validation at the application edge and prioritize library upgrades where vendor patches lag. (bleepingcomputer.com)
Strengths and cautionary risks — critical analysis
Notable strengths in Microsoft’s approach this month
- The inclusion of audit‑first enforcement tooling for SMB shows Microsoft is trying to balance security hardening with operational continuity; it helps avoid breaking legacy customers by enabling discovery before enforcement. This is a practical, risk‑conscious approach when hardening authentication subsystems at scale. (secpod.com)
- Packaging SSU+LCU together simplifies sequencing in many enterprise pipelines and reduces the classic “missing servicing stack” errors that previously created update headaches. (support.microsoft.com)
- Microsoft’s product KBs and per‑CVE documentation provide explicit remediation and any vendor‑recommended mitigations, which is essential for enterprise control planes. (support.microsoft.com)
Potential risks and operational downsides
- Combined SSU packages complicate rollback: once a servicing stack update is applied, rollback may be non‑trivial and require image re‑installs or restored snapshots. This elevates the importance of pre‑patch snapshots and tested restore procedures.
- SMB hardening and legacy cipher migration (DES removal scenarios noted in Microsoft advisory kernels) can break old appliances and services if organizations flip enforcement without first remediating compatibility issues. Treat DES migration as an operational program rather than a single‑patch event.
- Discrepancies across vendor reports (counts and zero‑day proclamations) create confusion; inconsistent public messaging increases the chance of under‑ or over‑prioritizing patches unless teams validate directly against Microsoft’s Security Update Guide. (intruceptlabs.com)
Who should act immediately
- Administrators of internet‑facing services (SharePoint, public SQL instances, RDP, SMB shares).
- Teams managing domain controllers and identity infrastructure (Kerberos/NTLM) — these are central to lateral movement risks.
- Operators of virtualization and hypervisor hosts (Hyper‑V, cloud hypervisors) and those running HPC clusters with exposed management ports. (securityaffairs.com)
Final takeaways
September’s Patch Tuesday is large and operationally consequential: it combines critical remote code execution fixes, a heavy cluster of elevation‑of‑privilege vulnerabilities, and important hardening controls that change how administrators should test and enforce security settings. Headline counts vary across trackers — expect to see numbers from roughly 80 to 86 CVEs depending on counting rules — and treat discrepancies about zero‑day status carefully by verifying Microsoft’s MSRC bulletin and KBs. (securityweek.com)Operational guidance in one line: inventory, snapshot, pilot, validate, then stage — with highest immediacy for internet‑facing RCEs, domain controllers, and hypervisors. Use Microsoft’s official KBs and the Security Update Guide as the single source of truth for CVE ↔ KB mapping and exploitability guidance before making deployment decisions. (support.microsoft.com)
Conclusion: the September release strengthens platform security substantially, but it requires disciplined execution and careful compatibility testing. Treat the vendor advisories and readiness infographics as operational planning tools, not a substitute for inventory‑based risk triage and validated pilot deployments. (support.microsoft.com)
Source: Computerworld For September, Patch Tuesday means fixes for Windows, Office and SQL Server