On 2026-05-15, CISA added CVE-2026-42897 (Microsoft Microsoft) to its Known Exploited Vulnerabilities (KEV) catalog [2]. The vulnerability is listed in the catalog as "Microsoft Exchange Server Cross-Site Scripting Vulnerability" [2]. CISA requires remediation in accordance with the listed vendor mitigation guidance; see the original text in the body for specific requirements [2].
Backfill: this event became public on May 15, 2026 and we added it on Nov 10, 2026. It is not a new event.
CISA Adds Microsoft Microsoft Vulnerability CVE-2026-42897 to Known Exploited Vulnerabilities Catalog
1 min read
- Disclosed
- May 15, 2026
- Published
- Nov 10, 2026
- Last updated
- Nov 8, 2026
- CVSS basis
- Our assessment
- 70.7%, higher than 99% of CVEs
- Exploitation and patch status
- ExploitedKEV
- Attack vector
- Vulnerability status
- Actor type
- Motivation
On this page
30-second summary
What happened
Who is affected
Industries mainly affected: Government, Cross-industry
What to do nowOur advice
CISA requires remediation in accordance with the listed vendor mitigation guidance; see the original text in the body for specific requirements [2].
Timeline
Technical details
CISA KEV Listing Record
CISA added CVE-2026-42897 (Microsoft Microsoft) to the Known Exploited Vulnerabilities () catalog on 2026-05-15 [2].
Original Technical Description
Microsoft Exchange Server contains a cross-site scripting vulnerability during web page generation in Outlook Web Access and when certain interaction conditions are met, arbitrary JavaScript can be executed in the browser context. [2]
Official 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. [2]
Individual Vulnerability Record
The U.S. National Vulnerability Database (NVD) provides an independent vulnerability record and description for CVE-2026-42897 [1].
References
Official / primary3
- [1]
“Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.”
- [2]
This site aggregates public information and is not security consulting advice. Test remediation steps before applying.