CVE-2026-29129
HIGHCVE-2026-29129 is a high-severity (CVSS 7.5) Broken Cryptographic Algorithm vulnerability in org.apache.tomcat:tomcat-coyote. O3 Security confirms whether CVE-2026-29129 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Apache Tomcat: TLS cipher order is not preserved
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.
- 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-2026-29129.
Real-World Exposure
org.apache.tomcat:tomcat-coyote☕org.apache.tomcat:tomcat-coyote☕org.apache.tomcat:tomcat-coyote☕org.apache.tomcat:tomcat☕org.apache.tomcat:tomcat☕org.apache.tomcat:tomcat☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core+1 moreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Configured cipher preference order not preserved vulnerability in Apache Tomcat.
This issue affects Apache Tomcat: from 11.0.16 through 11.0.18, from 10.1.51 through 10.1.52, from 9.0.114 through 9.0.115.
Users are recommended to upgrade to version 11.0.20, 10.1.53 or 9.0.116, which fix the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.tomcat:tomcat-coyote | ≥ 9.0.114&&< 9.0.116 | 9.0.116 |
| ☕Maven | org.apache.tomcat:tomcat-coyote | ≥ 10.1.51&&< 10.1.53 | 10.1.53 |
| ☕Maven | org.apache.tomcat:tomcat-coyote | ≥ 11.0.16&&< 11.0.20 | 11.0.20 |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 9.0.114&&< 9.0.116 | 9.0.116 |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 10.1.51&&< 10.1.53 | 10.1.53 |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 11.0.16&&< 11.0.20 | 11.0.20 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.tomcat:tomcat-coyote. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.apache.tomcat:tomcat-coyote to 9.0.116 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-29129 is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether CVE-2026-29129 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-29129. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
Low impact. A flaw in Apache Tomcat allows the configured cipher preference order to be bypassed. This could lead to a server using a weaker cipher than intended, potentially reducing the security posture of TLS connections. This affects Red Hat Enterprise Linux systems running Apache Tomcat.
Frequently Asked Questions
Is CVE-2026-29129 in your dependencies?
O3 detects CVE-2026-29129 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.