What is CVE-2026-21514?
Reliance on untrusted inputs in a security decision in Microsoft Office Word allows an unauthorized attacker to bypass a security feature locally.
The record classifies CVE-2026-21514 under weakness class CWE-807. Its CVSS v3 base vector states that the flaw requires local access to the host, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 8 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 260 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 7.8 — HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - EPSS (FIRST)
- 1.6% probability of exploitation in the next 30 days, higher than 75.0% of all scored CVEs
- CISA KEV
- Listed since 2026-02-10, federal remediation deadline 2026-03-03
- Threadlinqs priority
- 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
- Published
- 2026-02-10, last modified 2026-08-19
Is CVE-2026-21514 being exploited?
CISA added CVE-2026-21514 to the Known Exploited Vulnerabilities catalog on 2026-02-10, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-03-03 under BOD 22-01. Weaponised exploit code for CVE-2026-21514 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 47 in the Threadlinqs vulnerability feed.
Affected products and versions
- Microsoft: 365 Apps, Office Long Term Servicing Channel 2021, Office Long Term Servicing Channel 2024
Showing 3 of 8 recorded product entries.
How to fix CVE-2026-21514
Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21514. Because CVE-2026-21514 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-03-03. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-21514
2 tracked threats in the Threadlinqs corpus reference CVE-2026-21514, either in the campaign’s CVE list or as an indicator on the campaign record.
- February 2026 Patch Tuesday: Six Zero-Days Among 59 CVEs — CrowdStrike-Discovered RDP EoP Exploited Since December 2025 — CRITICAL · 2026-02-12
- February 2026 Patch Tuesday: Six Zero-Days Among 59 CVEs — CRITICAL · 2026-02-12
Sources
Enriched from CVE.org, FIRST EPSS, CISA KEV, public proof-of-concept repositories. Last verified by Threadlinqs on .