Microsoft Excel: Remote code execution due to double free
Summary
A double free vulnerability (CWE-415) in Microsoft Office Excel allows an unauthorized attacker to execute code over a network. Exploitation requires user interaction, for example opening a manipulated spreadsheet received by email or download. Microsoft rates the flaw as Important with a CVSS 3.1 base score of 8.8.
Affected
- Microsoft 365 Apps for Enterprise (16.0.1 up to the version listed at https://aka.ms/OfficeSecurityReleases)
- Office 365 for Mac (1.0.0 to before 16.114.26101123)
- Office LTSC 2021 (16.0.1 to before 16.0.14334.20974)
- Office LTSC 2024 (16.0.0 to before 16.0.17932.21056)
- Office LTSC for Mac 2021 (16.0.1 to before 16.114.26101123)
- Office LTSC for Mac 2024 (16.0.0 to before 16.114.26101123)
- Office Online Server (16.0.0.0 to before 16.0.10417.20228)
Fixed in
- Office LTSC 2021: 16.0.14334.20974 or later
- Office LTSC 2024: 16.0.17932.21056 or later
- Office 365 for Mac and LTSC for Mac: 16.114.26101123 or later
- Office Online Server: 16.0.10417.20228 or later
- Microsoft 365 Apps for Enterprise: fixed build not confirmed; see the MSRC page
- Build numbers as listed in the CVE record; confirm against the MSRC Security Update Guide before writing patch rules
Workaround
No vendor-documented workaround found. The MSRC mitigation section was not verified.
Exploitation
- Exploited in the wild: no evidence found; not listed in CISA KEV at the time of research.
- Public proof of concept: none found; Microsoft marks the CVE as not publicly disclosed.
- CISA SSVC: exploitation none, automatable no, technical impact total.
Our recommendation
- Install the October 2026 Microsoft Office security update on all Excel installations, including Microsoft 365 Apps, LTSC and Mac versions.
- Prioritise Office Online Server, especially if it is published to the internet, and apply KB5002928 or the matching build.
- Check the MSRC page and CISA KEV weekly for changes in exploitation status.
- Remind users not to open unexpected spreadsheets from unknown senders.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Remote code execution – Microsoft Office Excel
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Microsoft Office
- Updates (KB)
- KB5002928
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-97772 msrc.microsoft.com
- Microsoft 365 Apps security updates learn.microsoft.com
- Release notes: Office for Mac learn.microsoft.com
- Office Online Server update KB5002928 support.microsoft.com
- OpenCVE: CVE-2026-97772 app.opencve.io
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 31 Oct 2026, 17:18.
Original description (NVD)
Double free in Microsoft Office Excel 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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