How to check if you are exposed to CVE-2026-42897
- Find every Microsoft 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-2026-42897.
US federal agencies had to fix this by 2026-05-29. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.
Affected versions
Versions the National Vulnerability Database lists as vulnerable to CVE-2026-42897. Check the vendor advisory for the exact fixed builds before you sign anything off.
| Product | Vulnerable versions |
|---|---|
| Microsoft Exchange Server | 2016; 2016-cumulative_update_1; 2016-cumulative_update_10; 2016-cumulative_update_11; 2016-cumulative_update_12; 2016-cumulative_update_13 and 33 more |
| Microsoft Exchange Server Subscription Edition | before 15.02.2562.043 |
Timeline
- · Published in the National Vulnerability Database
- · Added to CISA's Known Exploited Vulnerabilities catalog, 1 day after it was published
- · Fix-by date for US federal agencies, passed 156 days ago
Vendor advisories and fixes
Weakness type
More exploited Microsoft vulnerabilities
CISA lists 390 exploited Microsoft vulnerabilities. The closest matches:
- CVE-2026-96951Microsoft Windows Command Injection VulnerabilityAdded 2026-10-13
- CVE-2026-65660Microsoft SharePoint Code Injection VulnerabilityAdded 2026-09-25
- CVE-2026-85880Microsoft Windows Heap-Based Buffer Overflow VulnerabilityAdded 2026-09-08
- CVE-2026-81963Microsoft Windows Link Following VulnerabilityAdded 2026-09-08
- CVE-2019-1068Microsoft SQL Server Remote Code Execution VulnerabilityAdded 2026-08-26
- CVE-2026-55040Microsoft SharePoint Weak Authentication VulnerabilityAdded 2026-08-18
- CVE-2026-33824Microsoft Internet Key Exchange (IKE) Service Extensions Double Free VulnerabilityAdded 2026-08-18
- CVE-2026-68820Microsoft Windows Ancillary Function Driver for WinSock Use-After-Free VulnerabilityAdded 2026-08-11
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.