How to check if you are exposed to CVE-2021-31196
- Find every Microsoft Exchange Server 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 below. 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-2021-31196.
US federal agencies had to fix this by 2024-09-11. 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 781 days ago
Vendor advisories and fixes
More exploited Microsoft vulnerabilities
CISA lists 390 exploited Microsoft vulnerabilities. The closest matches:
- CVE-2023-21529Microsoft Exchange Server Deserialization of Untrusted Data VulnerabilityAdded 2026-04-13
- CVE-2024-21410Microsoft Exchange Server Privilege Escalation VulnerabilityAdded 2024-02-15
- CVE-2022-41080Microsoft Exchange Server Privilege Escalation VulnerabilityAdded 2023-01-10
- CVE-2022-41082Microsoft Exchange Server Remote Code Execution VulnerabilityAdded 2022-09-30
- CVE-2022-41040Microsoft Exchange Server Server-Side Request Forgery VulnerabilityAdded 2022-09-30
- CVE-2018-8581Microsoft Exchange Server Privilege Escalation VulnerabilityAdded 2022-03-03
- CVE-2021-33766Microsoft Exchange Server Information DisclosureAdded 2022-01-18
- CVE-2021-34523Microsoft Exchange Server Privilege Escalation VulnerabilityAdded 2021-11-03
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.