CVE-2023-34981 is a high-severity (CVSS 7.5) CWE-732 vulnerability in org.apache.tomcat.embed:tomcat-embed-core. A fix is available for org.apache.tomcat.embed:tomcat-embed-core — see the affected versions and patch details below.
Apache Tomcat: AJP response header mix-up
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-2023-34981.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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-coyoteReal-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
A regression in the fix for bug 66512 in Apache Tomcat 11.0.0-M5, 10.1.8, 9.0.74 and 8.5.88 meant that, if a response did not include any HTTP headers no AJP SEND_HEADERS messare woudl be sent for the response which in turn meant that at least one AJP proxy (mod_proxy_ajp) would use the response headers from the previous request leading to an information leak.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 11.0.0-M5&&< 11.0.0-M6 | 11.0.0-M6org.apache.tomcat.embed:tomcat-embed-core:11.0.0-M6 |
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 10.1.8&&< 10.1.9 | 10.1.9org.apache.tomcat.embed:tomcat-embed-core:10.1.9 |
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 9.0.74&&< 9.0.75 | 9.0.75org.apache.tomcat.embed:tomcat-embed-core:9.0.75 |
| ☕Maven | org.apache.tomcat:tomcat-coyote | ≥ 8.5.88&&< 8.5.89 | 8.5.89org.apache.tomcat:tomcat-coyote:8.5.89 |
Affected Products
tomcatapacheDetection & 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.tomcat.embed:tomcat-embed-core to 11.0.0-M6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-34981 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.
Frequently Asked Questions
Is CVE-2023-34981 in your dependencies?
Find it across Maven, including transitive dependencies.