CVE-2026-42897 — Security Box Score

CVE · referencelatest edition

Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-42897HIGH

Microsoft Exchange Server Spoofing Vulnerability

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   R  U  H  H  N    8.1   .7031   99.3   YES

AFFECTED
  Product                                              Versions     Fixed
  Microsoft Exchange Server 2016 Cumulative Update 23  15.01.0.0 –  —
  Microsoft Exchange Server 2019 Cumulative Update 14  15.02.0.0 –  —
  Microsoft Exchange Server 2019 Cumulative Update 15  15.02.0.0 –  —
  Microsoft Exchange Server Subscription Edition RTM   15.02.0.0 –  —

TIMELINE
  Apr 30  Reserved by microsoft
  May 15  Added to CISA KEV, remediation due 2026-05-29
  May 15  Published (CNA: microsoft)
  May 30  DUE DATE PASSED — CVE-2026-42897 (Microsoft Exchange Server 2016 Cumulative Update 23). CISA remediation deadline was May 29, 2026; still in catalog.

CWE-79 · CNA: microsoft · CVSS v3.1 · 2 references · KEV due May 29, 2026

Description

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.

Lifecycle

Complete event history — 4 events, chronological
Date	Event	Detail
April 30, 2026	Reserved	Reserved by microsoft
May 15, 2026	KEV ADDED	Added to CISA KEV, remediation due 2026-05-29
May 15, 2026	Published	Published (CNA: microsoft)
May 30, 2026	DUE DATE PASSED	DUE DATE PASSED — CVE-2026-42897 (Microsoft Exchange Server 2016 Cumulative Update 23). CISA remediation deadline was May 29, 2026; still in catalog.

Affected

Affected products and packages — 4 rows
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
Microsoft	Microsoft Exchange Server 2016 Cumulative Update 23	—	15.01.0.0	—
Microsoft	Microsoft Exchange Server 2019 Cumulative Update 14	—	15.02.0.0	—
Microsoft	Microsoft Exchange Server 2019 Cumulative Update 15	—	15.02.0.0	—
Microsoft	Microsoft Exchange Server Subscription Edition RTM	—	15.02.0.0	—

Weaknesses

CWE-79

References (2)

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42897 [vendor-advisory, patch]
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-42897 [government-resource]

Authoritative record: CVE-2026-42897 at cve.org

Vendors: microsoft

Weaknesses: CWE-79

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-42897 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.