CVE-2026-42897
CRITICALCISA KEVEPSS 99th pctlDescription
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 to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N/E:F/RL:O/RC:C
Exploit Intelligence
Very high risk: more likely to be exploited than 99% of all known CVEs.
Remediation due: 2026-05-29
References
Related Vulnerabilities
Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2018-12998 | Medium | 6.1 | 99% | - | - |
| CVE-2020-11022 | Medium | 6.9 | 99% | - | Fix |
| CVE-2019-3929 | Critical | 9.8 | 99% | KEV | Fix |
| CVE-2020-9496 | Medium | 6.1 | 99% | - | - |
| CVE-2023-28341 | Medium | 6.1 | 99% | - | Fix |
| CVE-2025-4123 | High | 7.6 | 98% | - | Fix |
Common questions
How do I fix CVE-2026-42897?
Published advisories record a fix for 4 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-42897 being actively exploited?
Yes. CVE-2026-42897 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. US federal agencies were required to remediate it by 2026-05-29. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2026-42897?
CVE-2026-42897 has a CVSS v3 base score of 8.1, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-42897 affect?
Published advisories record a fix for Microsoft Exchange Server 2016 Cumulative Update 23 (Microsoft), Microsoft Exchange Server 2019 Cumulative Update 14 (Microsoft), Microsoft Exchange Server 2019 Cumulative Update 15 (Microsoft), Microsoft Exchange Server Subscription Edition RTM (Microsoft). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-15.