Microsoft Office Excel: Out-of-bounds read leads to information disclosure
Summary
An out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network. Exploitation requires a victim to open a crafted file, typically delivered by email or download. The impact is limited to confidentiality, as integrity and availability are not affected according to the CVSS vector.
Affected
- Microsoft 365 Apps for Enterprise (16.0.1 before the build listed at https://aka.ms/OfficeSecurityReleases)
- Microsoft Office 365 for Mac (1.0.0 before 16.115.26110837)
- Microsoft Office LTSC 2021 (16.0.1 before 16.0.14334.21048)
- Microsoft Office LTSC 2024 (16.0.0 before 16.0.17932.21140, according to a third-party tracker; not confirmed in the CNA record)
- Microsoft Office LTSC for Mac 2021 and 2024 (16.0.1 / 16.0.0 before 16.115.26110837)
Fixed in
- Office LTSC 2021: 16.0.14334.21048 or later
- Office 365 for Mac and LTSC for Mac: 16.115.26110837 or later
- Microsoft 365 Apps for Enterprise: build listed at https://aka.ms/OfficeSecurityReleases (exact number unknown)
- Office LTSC 2024: 16.0.17932.21140 according to a third-party tracker; verify in MSRC
- Released with the November 2026 Patch Tuesday (November 10, 2026)
Workaround
No official workaround or mitigation is available.
- Warn users about unexpected Excel attachments
- Keep Protected View enabled for files from the internet
- Use email filtering and attachment sandboxing
Exploitation
- Not known to be exploited in the wild (the exploited Outlook flaw is CVE-2026-124194, not this CVE)
- Rapid7 rates exploitation as Less Likely, with no public disclosure
- No public proof of concept found
Our recommendation
- Deploy the November 2026 Office updates to all Microsoft 365 Apps and LTSC 2021/2024 clients, including Mac
- Verify the fixed build for each channel in the MSRC advisory, as sources disagree on LTSC 2024
- Keep Protected View and macro restrictions enabled
- Filter .xlsx and .xlsm attachments from external senders
- Raise user awareness about phishing with Excel attachments
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 Update Guide: CVE-2026-119999 msrc.microsoft.com
- CVE Record CVE-2026-119999 www.cve.org
- Rapid7: Patch Tuesday November 2026 www.rapid7.com
- Action1: Patch Tuesday November 2026 www.action1.com
- Threatint: CVE-2026-119999 cve.threatint.com
- Strix: CVE-2026-119999 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, 12:05.
Original description (NVD)
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information 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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