Heap-based buffer overflow in Microsoft products - CVE-2026-81955

Vulnerability identifier: #VU148303

CSH Severity: High

CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-81955

CWE-ID: CWE-122

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to execute code.

The vulnerability exists due to a heap-based buffer overflow in Microsoft Graphics Component when processing a specially crafted RTF file in Microsoft Word. A remote attacker can send a specially crafted RTF file and convince a user to open it in Microsoft Word and save it as a filtered web page to execute code.

The Preview Pane is not an attack vector.

Microsoft Windows
Windows Server
Microsoft 365 Apps for Enterprise
Microsoft Office

Install security update from vendor's website.

Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7725, 10 22H2 10.0.19045.7725, 10 1607 10.0.14393.9504, 10 1809 10.0.17763.9245, 11 23H2 10.0.22631.7582, 11 24H2 10.0.26100.9445, 11 25H2 10.0.26200.9445, 11 26H1 10.0.28000.2954
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Office - addressed in versions 16.0.5569.1003, 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976
Windows Server - addressed in versions 2012 R2 6.3.9600.23397, 2012 6.2.9200.26349, 2016 10.0.14393.9504, 2019 10.0.17763.9245, 2022 10.0.20348.5622, 2025 10.0.26100.33438

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-81955

• Remote code execution in Windows Graphics component