Apache Tomcat AJP Thread Pinning DoS (pre11.0.26, pre10.1.60, pre9.0.122)
CVE-2026-78383 Published on September 23, 2026
Apache Tomcat: AJP DoS via missing request body
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.
Vulnerability Analysis
CVE-2026-78383 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
Allocation of Resources Without Limits or Throttling
The software allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.
Products Associated with CVE-2026-78383
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Affected Versions
Apache Software Foundation Apache Tomcat:- Version 11.0.0-M1, <= 11.0.25 is affected.
- Version 10.1.0-M1, <= 10.1.59 is affected.
- Version 9.0.0.M1, <= 9.0.121 is affected.
- Version 8.5.0, <= 8.5.100 is affected.
- Version 7.0.0, <= 7.0.109 is affected.