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Description

Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.

PUBLISHED Reserved 2025-12-30 | Published 2026-01-26 | Updated 2026-01-26 | Assigner microsoft




HIGH: 7.8CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

Problem types

CWE-807: Reliance on Untrusted Inputs in a Security Decision

Product status

19.0.0 (custom) before https://aka.ms/OfficeSecurityReleases
affected

16.0.1 (custom) before https://aka.ms/OfficeSecurityReleases
affected

16.0.1 (custom) before https://aka.ms/OfficeSecurityReleases
affected

16.0.0 (custom) before https://aka.ms/OfficeSecurityReleases
affected

16.0.0 (custom) before 16.0.5539.1001
affected

References

www.cisa.gov/...erabilities-catalog?field_cve=CVE-2026-21509 government-resource

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509 (Microsoft Office Security Feature Bypass Vulnerability) vendor-advisory patch

cve.org (CVE-2026-21509)

nvd.nist.gov (CVE-2026-21509)

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