How severe is CVE-2026-21514?

CVE-2026-21514 has a CVSS score of 7.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-21514?

Affected package information for CVE-2026-21514 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2026-21514?

No fixed version has been published for CVE-2026-21514 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2026-21514 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2026-21514, including . All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2026-21514?

CVE-2026-21514 has an EPSS (Exploit Prediction Scoring System) score of 5.4%, placing it in the 90th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2026-21514 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2026-21514 (Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-02-10. CISA required all US federal civilian agencies to remediate this vulnerability by 2026-03-03. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2026-21514?

CVE-2026-21514 is classified as CWE-807 (CWE-807). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2026-21514?

CVE-2026-21514 affects microsoft 365 apps; microsoft office long term servicing channel (2 versions, e.g. 2021, 2024). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2026-21514 published, and has it been updated?

CVE-2026-21514 was published on February 10, 2026 and was last updated on February 11, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2026-02-10 — agencies required to remediate by 2026-03-03

CVE-2026-21514

HIGH

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

Published

Feb 10, 2026

Updated

Feb 11, 2026

Affected

0 pkgs

Patched

None yet

Exploits

1 known

EPSS Exploitation Probability

via FIRST.org ↗

5.4%probability of exploitation in next 30 days

Lower Risk90th percentile+0.43%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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

Affected Products

2 products · 8 configurations

Application

365 appsmicrosoft

all

Application

office long term servicing channelmicrosoft

2 versions

20212024

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

ChaitanyaHaritash/CVE-2026-21514_CVE-2026-21510

CVE-2026-21514 & CVE-2026-21510 (Because MS-Office Fascinates me)

⭐ 3🍴 0May 2026

Frequently Asked Questions

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

O3 Security · Impact-Aware SCA

Is CVE-2026-21514 in your stack?

O3 detects CVE-2026-21514 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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