Microsoft Monthly Security Update (September 2026)
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
Details
Original advisory: https://www.hkcert.org/security-bulletin/microsoft-monthly-security-update-september-2026-_20260909
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Exploitation confirmedCVE-2026-81963Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 48% of all EPSS-scored CVEs.
- Exploitation confirmedCVE-2026-85880Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 45% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-81963 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-85880 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- unknownexploitedNCSC-2026-0353 [1.01] [M/H] Kwetsbaarheden verholpen in Microsoft Windowsncsc-nl
- unknownexploitedSecurity Alert: Microsoft Releases September 2026 Security Updatesjpcert
- unknownexploitedMultiples vulnérabilités dans Microsoft Windows (09 septembre 2026)cert-fr-avis
- unknownexploitedMicrosoft security advisory – September 2026 monthly rollup (AV26-896) – Update 1cccs
- highexploitedCVE-2026-85880: Heap-based buffer overflow in Windows ALPC allows an authorized attacker to elevate privileges…nvd
- highexploitedCVE-2026-81963: Improper link resolution before file access ('link following') in Windows Update Stack allows …nvd
- highexploitedCISA Adds Four Known Exploited Vulnerabilities to Catalogcisa
- highexploitedCVE-2026-81963: Windows Update Stack Elevation of Privilege Vulnerabilitymsrc
- highexploitedCVE-2026-85880: Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerabilitymsrc
- criticalexploitedCVE-2026-81963: Microsoft Windows Link Following Vulnerabilitycisa-kev
- criticalexploitedCVE-2026-85880: Microsoft Windows Heap-Based Buffer Overflow Vulnerabilitycisa-kev
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