Vulnerability · CVE-2026-42897
Microsoft Exchange Server Cross-Site Scripting Vulnerability
Published May 14, 2026 · catalog updated Jun 17, 2026 · Microsoft Microsoft
Patch now
CVE-2026-42897 is in the CISA known-exploited catalog, due May 29, 2026. Confirm Microsoft Microsoft against the vendor advisory and apply that fix. The CVSS score does not change the priority.
Gaps on this record
- No version range is stored. A customer cannot check an installed version against this record.
- Severity
- Medium6.1
- Known exploitation
- CISA KEV and VulnCheck KEV
- EPSS
- 0.52%
- Remediation
- Remediation guidance
- Affected products
- cpe microsoft/exchange server · vendor Microsoft Microsoft
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.
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- cpe microsoft/exchange server2016
- vendor Microsoft Microsoftversion unspecified
How to fix CVE-2026-42897
Recommended remediation
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. CISA due date May 29, 2026.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
CVE-2026-42897 is in the CISA known-exploited catalog, due May 29, 2026. Confirm Microsoft Microsoft against the vendor advisory and apply that fix. The CVSS score does not change the priority.
Which versions are affected?
Compare what you have installed with microsoft/exchange server 2016. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
What should an analyst verify?
CWE-79: Cross-site Scripting (XSS). EPSS 0.52%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
May 14, 2026 · Catalog
Detected
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.
May 15, 2026 · CISA KEV
Known exploited
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
May 29, 2026 · CISA KEV
Remediation due
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Jun 17, 2026 · Catalog
Updated
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.
Jun 17, 2026 · NIST NVD
Updated
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.
Sources
- CISA KEVConfirmed exploitationCVE-2026-42897
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.
cisa.gov - CVE.orgVulnerability recordCVE-2026-42897
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-42897
30-day exploitation probability 0.5%
first.org - NIST NVDVulnerability recordCVE-2026-42897
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.
nvd.nist.gov - VulnCheck KEVConfirmed exploitationCVE-2026-42897
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.
vulncheck.com
References
- VulnCheck exploitation evidence · api.msrc.microsoft.com
- VulnCheck exploitation evidence · asec.ahnlab.com
- VulnCheck exploitation evidence · docs.google.com
- CISA note · learn.microsoft.com
- CISA note · msrc.microsoft.com
- VulnCheck exploitation evidence · msrc.microsoft.com
- Mitigation · msrc.microsoft.com
- CISA note · nvd.nist.gov
- US Government Resource · cisa.gov
- VulnCheck exploitation evidence · cisa.gov
- VulnCheck exploitation evidence · proofpoint.com
Freshness
Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.