VulnerabilityAnalyzed

CVE-2026-21514

Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision Vulnerability

KEVHIGH 7.8EPSS 1.54%

Does this matter?

Known to be exploited in the wild (CISA KEV, CISA remediation deadline 3 March 2026). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.

Description

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

CVSS 3.1: 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS: 1.54% probability · 74th percentile
CISA KEV: Listed 10 February 2026 · due 3 March 2026
Weakness: CWE-807
Affected: microsoft/365 apps · microsoft/office long term servicing channel
Source: secure@microsoft.com

CISA notes

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21514 ; https://nvd.nist.gov/vuln/detail/CVE-2026-21514

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21514Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21514US Government Resource

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.