CVE-2026-78383
Received Received - Intake

Allocation of Resources Without Limits in Apache Tomcat Leads to DoS

Publication date: 2026-09-23

Last updated on: 2026-09-23

Assigner: Apache Software Foundation

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.

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Meta Information

Published
2026-09-23
Last Modified
2026-09-23
Generated
2026-09-23
AI Q&A
2026-09-23
EPSS Evaluated
N/A
NVD
CVE-2026-78383
EUVD
EUVD-2026-85230

Affected Vendors & Products

Showing 5 associated CPEs
Vendor Product Version / Range
apache tomcat From 11.0.0-M1 (inc) to 11.0.25 (inc)
apache tomcat From 10.1.0-M1 (inc) to 10.1.59 (inc)
apache tomcat From 9.0.0.M1 (inc) to 9.0.121 (inc)
apache tomcat From 8.5.0 (inc) to 8.5.100 (inc)
apache tomcat From 7.0.0 (inc) to 7.0.109 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Attack-Flow Graph

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Executive Summary

This vulnerability in Apache Tomcat allows an unauthenticated AJP request to consume all available AJP processing threads, causing a denial of service by preventing the server from handling legitimate requests.

Detection Guidance

Detecting this vulnerability requires checking Apache Tomcat versions. Run: 'catalina.sh version' or 'java -cp catalina.jar org.apache.catalina.util.ServerInfo' to verify Tomcat version. If running 11.0.0-M1 to 11.0.25, 10.1.0-M1 to 10.1.59, 9.0.0.M1 to 9.0.121, 8.5.0 to 8.5.100, or 7.0.0 to 7.0.109, the system is vulnerable.

Impact Analysis

If exploited, this vulnerability can crash or severely degrade the performance of Apache Tomcat servers, leading to downtime for web applications relying on AJP protocol. Unpatched systems are at risk of service disruption.

Compliance Impact

This vulnerability could impact compliance with GDPR and HIPAA by enabling denial-of-service attacks that disrupt availability of Tomcat services. Unavailability of systems may violate requirements for timely access to personal or health data under these regulations.

Mitigation Strategies

Upgrade Apache Tomcat to version 11.0.26, 10.1.60, or 9.0.122 immediately. If using unsupported versions (8.5.x or 7.0.x), upgrade to a supported release or apply vendor patches if available.

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