Microsoft Windows Backup Engine: Use-after-free elevation of privilege
Summary
A use-after-free vulnerability in the Windows Backup Engine allows a local attacker with low privileges to elevate their rights on the affected system. Exploitation requires a local low-privileged account or code already running as a user, and the attack complexity is high. The vulnerability is not remotely exploitable; Microsoft rates it CVSS 3.1 7.0 (High), and no exploitation in the wild or public proof of concept has been found.
Affected
- Windows 10 Version 21H2: 10.0.19044.0 to before 10.0.19044.7846
- Windows 10 Version 22H2: 10.0.19045.0 to before 10.0.19045.7846
- Windows 11 Version 23H2: 10.0.22631.0 to before 10.0.22631.7711
- Windows 11 Version 24H2 (per secondary source, unverified): 10.0.26100.0 to before 10.0.26100.9974
- Windows 11 Version 25H2 (per secondary source, unverified): 10.0.26200.0 to before 10.0.26200.9974
- Windows 11 Version 26H1 (per secondary source, unverified): 10.0.28000.0 to before 10.0.28000.3501
- Windows 11 Version 26H2 (per secondary source, unverified): 10.0.26300.0 to before 10.0.26300.9974
- Windows Server: Unknown.
Fixed in
- Install the November 2026 cumulative update for the affected Windows versions (fixed builds listed above).
- KB numbers per build: Unknown.
Workaround
- No vendor-published workaround known.
Exploitation
- No evidence of exploitation in the wild found.
- No public proof of concept found.
- CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
Our recommendation
- Install the November 2026 cumulative update on all affected Windows 10 and 11 systems, prioritising multi-user systems, terminal servers and hosts with a known user-level compromise.
- Verify build numbers and Windows Server coverage against the Microsoft Security Update Guide before rollout.
- Monitor for signs of local privilege escalation and review local accounts on shared systems.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Backup Engine
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5131096, KB5131087, KB5132061, KB5132043, KB5132059
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-119405 msrc.microsoft.com
- CVE Record CVE-2026-119405 www.cve.org
- VulDB CVE-2026-119405 vuldb.com
- Strix CVE-2026-119405 (secondary, version ranges unverified) www.strix.ai
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 11 Nov 2026, 08:48.
Original description (NVD)
Use after free in Windows Backup Engine allows an authorized attacker to elevate privileges locally.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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