CISA KEV · Known exploitedMedium

CVE-2026-42897

Microsoft

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.

CVSS
6.1
EPSS
70.3%
99.3% percentile
CISA KEV
Listed
Published
2026.05.15
PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV
Exploit probability70.3%
Technical severityCVSS 6.1

Vulnerability overview

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.

Affected product and versions

Product
Microsoft
Affected versions
15.01.0.0, 15.02.0.0, 2016, 2019, < 15.02.2562.043
Fixed versions
15.02.2562.043

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
CISA 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.

Due date: 2026.05.29
  1. 1
    Identify

    Confirm that Microsoft and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CWE
CWE-79
KEV added
2026.05.15
Ransomware use
미확인