Microsoft Office Word: Remote code execution via heap-based buffer overflow
Summary
A heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network. The attack requires a user to open a crafted Word document, for example an email attachment or a downloaded file. No internet-exposed service is involved, so phishing is the realistic attack path. CVSS 8.8 (High).
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 to before the fixed build (build number unknown, see MSRC)
- Office 365 for Mac: before 16.114.26101123
- Office LTSC 2021: before 16.0.14334.20974
- Office LTSC 2024: before 16.0.17932.21056
- Office LTSC for Mac 2021: before 16.114.26101123
- Office LTSC for Mac 2024: before 16.114.26101123
Fixed in
- Microsoft 365 Apps for Enterprise: Unknown. Take the fixed build from the MSRC advisory or Microsoft's Office security release page.
- Office 365 for Mac: 16.114.26101123
- Office LTSC 2021: 16.0.14334.20974
- Office LTSC 2024: 16.0.17932.21056
- Office LTSC for Mac 2021 and 2024: 16.114.26101123
Workaround
- No vendor workaround found. Patching is the recommended remedy.
- Possibly configure Office so that documents from network shares or other untrusted origins do not open automatically. The exact setting is unconfirmed; verify it against the MSRC advisory before rollout.
Exploitation
- Not listed in CISA KEV; no confirmed exploitation in the wild.
- No public exploit code has been confirmed.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- EPSS is below 1%.
Our recommendation
- Install the security updates for Microsoft 365 Apps and Office LTSC as soon as possible. Prioritize mail gateways, file servers and staff who handle external documents.
- Make sure automatic updates are enabled for Microsoft 365 Apps.
- Check the MSRC advisory for the fixed Microsoft 365 Apps build and verify installed versions.
- Warn users not to open unexpected Word attachments or files from untrusted sources.
- Monitor for exploitation and re-check the CISA KEV catalog and the vendor page regularly.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Response Center: CVE-2026-108449 msrc.microsoft.com
- OpenCVE: CVE-2026-108449 app.opencve.io
- VulDB: CVE-2026-108449 vuldb.com
- OffSeq Radar: CVE-2026-108449 radar.offseq.com
- ThreatInt: CVE-2026-108449 cve.threatint.com
- Vulners Vulnrichment: CVE-2026-108449 vulners.com
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, 16:16.
Original description (NVD)
Heap-based buffer overflow in Microsoft Office Word 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.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.