Widely deployed Tomcat; critical severity; affects multiple major versions; upgrade required.
CVE-2026-53434
Tomcat CRL config error leads to unhandled error condition.
Is CVE-2026-53434 being exploited?
Not confirmed. CVE-2026-53434 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.55% probability of exploitation in the next 30 days.
How severe is CVE-2026-53434?
CVE-2026-53434 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-53434?
Yes. A fix has been recorded for CVE-2026-53434. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-53434 affect?
CVE-2026-53434 affects Apache Tomcat 11.0.0-M1 through 11.0.22, Apache Tomcat 10.1.0-M7 through 10.1.55, Apache Tomcat 9.0.83 through 9.0.118. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-53434?
Upgrade to patched Tomcat versions (11.0.23, 10.1.56, 9.0.119) and verify CRL config.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unhandled error in CRL configuration may crash Tomcat or cause denial of service.
Immediate action required
- affected>= 11.0.0-M1 and <= 11.0.22
- affected>= 10.1.0-M7 and <= 10.1.55
- affected>= 9.0.83 and <= 9.0.118
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.