GHSA-wm9w-rjj3-j356 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in org.apache.tomcat.embed:tomcat-embed-core. O3 Security confirms whether GHSA-wm9w-rjj3-j356 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Apache Tomcat - Denial of Service
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 GHSA-wm9w-rjj3-j356.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-wm9w-rjj3-j356 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat:tomcat-coyote☕org.apache.tomcat:tomcat-coyote☕org.apache.tomcat:tomcat-coyote☕org.apache.tomcat:tomcat-coyote☕org.apache.tomcat.embed:tomcat-embed-coreReal-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
Improper Handling of Exceptional Conditions, Uncontrolled Resource Consumption vulnerability in Apache Tomcat. When processing an HTTP/2 stream, Tomcat did not handle some cases of excessive HTTP headers correctly. This led to a miscounting of active HTTP/2 streams which in turn led to the use of an incorrect infinite timeout which allowed connections to remain open which should have been closed.
This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.0-M20, from 10.1.0-M1 through 10.1.24, from 9.0.0-M1 through 9.0.89. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 though 8.5.100.
Users are recommended to upgrade to version 11.0.0-M21, 10.1.25 or 9.0.90, which fixes the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 11.0.0-M1&&< 11.0.0-M21 | 11.0.0-M21 |
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 10.1.0-M1&&< 10.1.25 | 10.1.25 |
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 9.0.0-M1&&< 9.0.90 | 9.0.90 |
| ☕Maven | org.apache.tomcat:tomcat-coyote | ≥ 11.0.0-M1&&< 11.0.0-M21 | 11.0.0-M21 |
| ☕Maven | org.apache.tomcat:tomcat-coyote | ≥ 10.1.0-M1&&< 10.1.25 | 10.1.25 |
| ☕Maven | org.apache.tomcat:tomcat-coyote | ≥ 9.0.0-M1&&< 9.0.90 | 9.0.90 |
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.embed:tomcat-embed-core. 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.embed:tomcat-embed-core to 11.0.0-M21 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wm9w-rjj3-j356 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 GHSA-wm9w-rjj3-j356 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 GHSA-wm9w-rjj3-j356. 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.
This vulnerability in Apache Tomcat is significant due to its impact on the stability and security of web applications relying on HTTP/2. The improper handling of excessive HTTP headers during HTTP/2 stream processing leads to an inaccurate count of active streams. This miscount causes the application to apply an…
Frequently Asked Questions
Is GHSA-wm9w-rjj3-j356 in your dependencies?
O3 detects GHSA-wm9w-rjj3-j356 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.