How severe is CVE-2026-42897?

CVE-2026-42897 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-42897 being actively exploited?

Yes. CVE-2026-42897 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-05-15, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2026-42897?

CVE-2026-42897 primarily affects Microsoft Exchange Server. In total, 40 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-42897?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2026-42897 have an EU (EUVD) identifier?

Yes. CVE-2026-42897 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30343. It is also flagged as exploited in the EUVD (since 2026-05-15).

When was CVE-2026-42897 published?

CVE-2026-42897 was published on 2026-05-14 and last updated on 2026-06-17.

CVE-2026-42897

CVE-2026-42897 is a high-severity vulnerability in Microsoft Exchange Server with a CVSS 3.x base score of 8.1. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2026-05-15). The underlying weakness is classified as CWE-79.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 6% (92nd percentile)
Actively exploited: Yes — listed in CISA KEV (added 2026-05-15)
EU (EUVD) id: EUVD-2026-30343
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2026-05-15)
Weakness: CWE-79
Affected product: Microsoft Exchange Server
Published: 2026-05-14
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-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.
How severe is CVE-2026-42897?: CVE-2026-42897 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-42897 being actively exploited?: Yes. CVE-2026-42897 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-05-15, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2026-42897?: CVE-2026-42897 primarily affects Microsoft Exchange Server. In total, 40 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-42897?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2026-42897 have an EU (EUVD) identifier?: Yes. CVE-2026-42897 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30343. It is also flagged as exploited in the EUVD (since 2026-05-15).
When was CVE-2026-42897 published?: CVE-2026-42897 was published on 2026-05-14 and last updated on 2026-06-17.

References

Affected products (40)

cpe:2.3:a:microsoft:exchange_server:2016:-:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_1:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_10:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_11:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_12:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_13:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_14:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_15:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_16:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_17:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_18:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_2:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_20:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_21:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_22:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_23:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_3:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_4:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_5:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_6:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_7:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_8:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_9:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:-:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_1:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_10:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_11:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_12:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_13:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_14:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_2:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_3:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_4:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_5:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_6:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_7:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_9:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server_subscription_edition:*:*:*:*:*:*:*:*

More vulnerabilities in Microsoft Exchange Server

CVE-2007-0213 — Critical (CVSS 10.0): Microsoft Exchange Server 2000 SP3, 2003 SP1 and SP2, and 2007 does not properly decode certain MIME encoded e-mails,…
CVE-2004-0840 — Critical (CVSS 10.0): The SMTP (Simple Mail Transfer Protocol) component of Microsoft Windows XP 64-bit Edition, Windows Server 2003, Windows…
CVE-2004-0574 — Critical (CVSS 10.0): The Network News Transfer Protocol (NNTP) component of Microsoft Windows NT Server 4.0, Windows 2000 Server, Windows…
CVE-1999-0385 — Critical (CVSS 10.0): The LDAP bind function in Exchange 5.5 has a buffer overflow that allows a remote attacker to conduct a denial of…
CVE-2024-21410 — Critical (CVSS 9.8): Microsoft Exchange Server Elevation of Privilege Vulnerability
CVE-2023-21709 — Critical (CVSS 9.8): Microsoft Exchange Server Elevation of Privilege Vulnerability

All CVEs affecting Microsoft Exchange Server →

Other CWE-79 (Cross-site Scripting (XSS)) vulnerabilities

CVE-2025-49410 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Imran Emu TC…
CVE-2024-47875 — Critical (CVSS 10.0): DOMPurify is a DOM-only, super-fast, uber-tolerant XSS sanitizer for HTML, MathML and SVG. DOMpurify was vulnerable to…
CVE-2024-6886 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Gitea…
CVE-2023-45144 — Critical (CVSS 10.0): com.xwiki.identity-oauth:identity-oauth-ui is a package to aid in building identity and service providers based on…
CVE-2023-45138 — Critical (CVSS 10.0): Change Request is an pplication allowing users to request changes on a wiki without publishing the changes directly.…
CVE-2022-4361 — Critical (CVSS 10.0): Keycloak, an open-source identity and access management solution, has a cross-site scripting (XSS) vulnerability in the…

Browse all CWE-79 (Cross-site Scripting (XSS)) vulnerabilities →