CVE-2026-21510: Microsoft Windows Shell Protection Mechanism Failure Vulnerability

What it is

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

Description quoted from the CVE record (assigned by microsoft, published 2026-02-10).

Weakness: CWE-693: Protection Mechanism Failure

How it can be exploited

Exploitable over the network with low attack complexity needing no privileges and a user must take an action. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: no. Technical impact: total.

On CISA KEV since

2026-02-10

US federal deadline

2026-03-03

Ransomware use

Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-01630, EUVD-2026-7337, GHSA-q6v4-4w5r-j7hr

Exploit Observer links 1 piece of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (1)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

• Code repository: https://github.com/andreassudo/cve-2026-21510-cvss-8.8-important-windows-shell-security-feature-bypass

Research and write-ups (1)

• Research or write-up: https://ptsecurity.com/research/trending-vulnerabilities/CVE-2026-21510

Vulnerability databases and vendor advisories (6)

Catalogue entries, not exploit evidence.

• Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-7337
• Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-q6v4-4w5r-j7hr
• Vulnerability database or vendor advisory: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-21510
• Vulnerability database or vendor advisory: https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-21510),
• Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-21510
• Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21510

19 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS

0.612
very likely to be attacked soon

VEDAS

0.658
some exploit evidence

On CISA KEV

Yes, since 2026-02-10

Detection rule

None yet

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.

Who is affected

2 more products are listed in the CVE record.

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: microsoft windows_10_1607, microsoft windows_10_1809, microsoft windows_10_21h2, microsoft windows_10_22h2, microsoft windows_11_23h2, microsoft windows_11_24h2, microsoft windows_11_25h2, microsoft windows_server_2012, microsoft windows_server_2016, microsoft windows_server_2019.

How to fix it

Fixed versions stated in the CVE record: 10.0.14393.8868, 10.0.17763.8389, 10.0.19044.6937, 10.0.19045.6937, 10.0.22631.6649, 10.0.26100.7840, 10.0.26200.7840, 10.0.28000.1575, 6.2.9200.25923, 6.3.9600.23022, 10.0.20348.4773, 10.0.25398.2149 and others.

CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor guidance:

• Windows Shell Security Feature Bypass Vulnerability (vendor-advisory, patch)

How to detect it

There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.

References

Vendor advisories and patches

• Windows Shell Security Feature Bypass Vulnerability (vendor-advisory, patch)

Government sources

• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21510 (government-resource)

Other databases

• CVE record (cve.org)
• NVD
• Exploit Observer

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.