Threat Intelligence / CVE / CVE-2026-21510

CVE-2026-21510 — Microsoft Windows 10 1607

CISA KEV
CVSS v3.1 8.8 (HIGH) · EPSS 3.5% (higher than 87.6% of all scored CVEs) · Priority 9/10 · Published 2026-02-10

As of 2026-02-11, CVE-2026-21510 is a HIGH-severity vulnerability in Microsoft Windows 10 1607, CVSS v3.1 8.8, EPSS 3.5% (87.6th 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 3 tracked threat campaigns to CVE-2026-21510, most recently “CVE-2026-32202 — Windows Shell Protection Mechanism Failure: NTLM Authentication Coercion via Auto-Parsed LNK Files (CISA KEV)”.

Last updated: 2026-02-11

What is CVE-2026-21510?

Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.

The record classifies CVE-2026-21510 under weakness class CWE-693. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 23 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
8.8 — HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS (FIRST)
3.5% probability of exploitation in the next 30 days, higher than 87.6% 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-2026-21510 being exploited?

CISA added CVE-2026-21510 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 14 of 23 recorded product entries.

How to fix CVE-2026-21510

Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21510. Because CVE-2026-21510 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-2026-21510

3 tracked threats in the Threadlinqs corpus reference CVE-2026-21510, 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-2026-21510 are available via the Threadlinqs MCP server (Purple tier). View plans →

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