CVE-2026-78383 Apache Tomcat: AJP DoS via missing request body
Unauthenticated attackers can cause denial of service in Apache Tomcat by sending AJP requests that pin processing threads without limits.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-78383?
CVE-2026-78383 is a high-severity denial of service vulnerability in Apache Tomcat, published on 23 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Allocation of resources without limits or throttling vulnerability in Apache Tomcat allows an unauthenticated AJP request to pin an AJP processing thread leading to denial of service.
This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.0.M1 through 9.0.121.
The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Other unsupported versions may also be affected.
Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.
Weakness: CWE-770
Which versions are affected by CVE-2026-78383?
1 open source package ship an affected version, including tomcat.
| Package | Affected | Fixed in |
|---|---|---|
tomcat Bitnami | From 7.0.0 | 9.0.45, 10.1.60, 11.0.26, 9.0.122 |
How do I fix CVE-2026-78383?
Upgrade tomcat to a fixed version for your release line: 9.0.45, 10.1.60, 11.0.26 or 9.0.122.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-78383 being exploited?
There is no known exploitation of CVE-2026-78383 in the wild and no public exploit code.
Sources
Also known as BIT-tomcat-2026-78383, DEBIAN-CVE-2026-78383, GHSA-rpxf-vjhq-9cv9, MINI-5648-664x-62x7, MINI-6h55-gq4p-38m3, MINI-mv5v-gq9v-ppcc and 1 more.