CVE-2026-53434 — tomcat
CRITICALCVE-2026-53434 is a critical-severity (CVSS 9.1) CWE-390 vulnerability. A fix is available — see the affected versions and patch details below.
Apache Tomcat: Invalid CRL configuration doesn't trigger failure for FFM Connector
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-53434.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-53434 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Description
Detection of Error Condition Without Action vulnerability in Apache Tomcat when configuring CRLs for a FFM based connector.
This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.22, from 10.1.0-M7 through 10.1.55, from 9.0.83 through 9.0.118.
Users are recommended to upgrade to version 11.0.23, 10.1.56 or 9.0.119, which fixes the issue.
Affected Products
tomcatapacheDetection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Fix
Upgrade the affected component to the fixed release for CVE-2026-53434, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
A flaw in Apache Tomcat's FFM-based connector causes errors loading configured Certificate Revocation Lists (CRLs) to be ignored, which could allow certificates that should be rejected to be accepted. Upstream affected versions are 9.0.83 through 9.0.118, 10.1.0-M7 through 10.1.55, and 11.0.0-M1 through 11.0.22. The…
This vulnerability only affects Tomcat deployments using the FFM-based connector (requires Java 22+) with CRL-based certificate revocation checking. Deployments using the standard NIO/NIO2 connectors or not using CRL checking are not affected.Source: Red Hat security advisory for CVE-2026-53434 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | tomcat9-1:9.0.120-1.el10_2 | RHSA-2026:68651 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | tomcat9-1:9.0.120-1.el10_0 | RHSA-2026:67163 |
| Red Hat Enterprise Linux 8 | tomcat-1:9.0.120-1.el8_10 | RHSA-2026:68677 |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | tomcat-1:9.0.120-1.el8_8 | RHSA-2026:68680 |
| Red Hat Enterprise Linux 9 | tomcat-1:9.0.120-2.el9_8 | RHSA-2026:68660 |
| Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | tomcat-1:9.0.120-1.el9_2 | RHSA-2026:68678 |
| Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions | tomcat-1:9.0.120-1.el9_4 | RHSA-2026:68679 |
| Red Hat Enterprise Linux 9.6 Extended Update Support | tomcat-1:9.0.120-1.el9_6 | RHSA-2026:68659 |
Frequently Asked Questions
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