How to check if you are exposed to CVE-2021-43890
- Find every Microsoft Windows system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
- Compare each version with the fixed versions in the vendor advisory. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
- Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2021-43890.
US federal agencies had to fix this by 2021-12-29. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.
Timeline
- · Added to CISA's Known Exploited Vulnerabilities catalog
- · Fix-by date for US federal agencies, passed 1,768 days ago
More exploited Microsoft vulnerabilities
CISA lists 390 exploited Microsoft vulnerabilities. The closest matches:
- CVE-2026-96951Microsoft Windows Command Injection VulnerabilityAdded 2026-10-13
- CVE-2026-85880Microsoft Windows Heap-Based Buffer Overflow VulnerabilityAdded 2026-09-08
- CVE-2026-81963Microsoft Windows Link Following VulnerabilityAdded 2026-09-08
- CVE-2008-4250Microsoft Windows Buffer Overflow VulnerabilityAdded 2026-05-20
- CVE-2026-32202Microsoft Windows Protection Mechanism Failure VulnerabilityAdded 2026-04-28
- CVE-2025-60710Microsoft Windows Link Following VulnerabilityAdded 2026-04-13
- CVE-2023-36424Microsoft Windows Out-of-Bounds Read VulnerabilityAdded 2026-04-13
- CVE-2008-0015 Microsoft Windows Video ActiveX Control Remote Code Execution VulnerabilityAdded 2026-02-17
Keep going
Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.