Microsoft Office: Remote code execution through use-after-free
Summary
A use-after-free vulnerability (CWE-416) in Microsoft Office allows an unauthenticated remote attacker to execute code. Exploitation requires a user to interact, typically by opening a malicious document delivered by email or download. The CVSS base score is 8.8 (HIGH), with high impact on confidentiality, integrity and availability.
Affected
- Microsoft 365 Apps for Enterprise (from 16.0.1, fixed build not confirmed in the sources)
- Office 365 for Mac (from 1.0.0 before 16.115.26110837)
- Office LTSC 2021 (from 16.0.1 before 16.0.14334.21048)
- Office LTSC 2024 (from 16.0.0 before 16.0.17932.21140)
- Office LTSC for Mac 2021 and 2024: conflicting information, unconfirmed
Fixed in
- Microsoft 365 Apps for Enterprise: Unknown (see https://aka.ms/OfficeSecurityReleases)
- Office 365 for Mac: 16.115.26110837
- Office LTSC 2021: 16.0.14334.21048
- Office LTSC 2024: 16.0.17932.21140
- Fix released with Microsoft's November 2026 Patch Tuesday
Workaround
Unknown. No mitigations are documented in the sources reviewed.
Exploitation
- No source links CVE-2026-111289 to active exploitation.
- CISA SSVC: exploitation none, not automatable, total technical impact.
- CVSS exploit code maturity is Unproven.
- No public proof of concept found.
Our recommendation
- Install the November 2026 Office updates on all affected Microsoft 365, Mac and LTSC clients as a priority.
- Confirm the fixed build for Microsoft 365 Apps and Office for Mac on the MSRC advisory.
- Until patched, be cautious with unsolicited Office attachments and downloads, and keep Protected View and macro restrictions enabled.
- Recheck NVD and CISA KEV for changes in exploitation status.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Response Center: CVE-2026-111289 msrc.microsoft.com
- CVE.org CNA record CVE-2026-111289 www.cve.org
- OffSeq: Microsoft November 2026 Patch Tuesday radar.offseq.com
- Strix: CVE-2026-111289 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 10 Nov 2026, 23:17.
Original description (NVD)
Use after free in Microsoft Office allows an unauthorized attacker to execute code over a network.
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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