Threat Intelligence / CVE / CVE-2026-21514

CVE-2026-21514 — Microsoft Office Long Term Servicing Channel

CISA KEV
CVSS v3.1 7.8 (HIGH) · EPSS 4.2% (higher than 88.8% of all scored CVEs) · Priority 9/10 · Published 2026-02-10

As of 2026-02-11, CVE-2026-21514 is a HIGH-severity vulnerability in Microsoft Office Long Term Servicing Channel, CVSS v3.1 7.8, EPSS 4.2% (88.8th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-02-10), with a US federal remediation deadline of 2026-03-03. Threadlinqs Intelligence links 2 tracked threat campaigns to CVE-2026-21514, most recently “February 2026 Patch Tuesday: Six Zero-Days Among 59 CVEs — CrowdStrike-Discovered RDP EoP Exploited Since December 2025”.

Last updated: 2026-02-11

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 215 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)
4.2% probability of exploitation in the next 30 days, higher than 88.8% 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 2026-02-11

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. It currently carries a trending score of 42 in the Threadlinqs vulnerability feed.

Affected products and versions

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.

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2026-21514 are available via the Threadlinqs MCP server (Purple tier). View plans →

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