Uncontrolled Resource Consumption in Apache Tomcat

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2020-11996: 26.70% estimated exploitation activity in the next 30 days; percentile 98.03 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

A specially crafted sequence of HTTP/2 requests sent to Apache Tomcat 10.0.0-M1 to 10.0.0-M5, 9.0.0.M1 to 9.0.35 and 8.5.0 to 8.5.55 could trigger high CPU usage for several seconds. If a sufficient number of such requests were made on concurrent HTTP/2 connections, the server could become unresponsive.

Published by the source

9 Feb 2022, 23:01 UTC

Last modified by the source

11 Jun 2026, 14:28 UTC

Source last checked

26 Oct 2026, 16:46 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-53hp-jpwq-2jgq

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# Patch Next advisory brief: CVE-2020-11996

Advisory: Uncontrolled Resource Consumption in Apache Tomcat
IDs: CVE-2020-11996, GHSA-53hp-jpwq-2jgq
Record: https://patchnext.com/advisories/cve-2020-11996 (revision 1, source checked 26 Oct 2026, 16:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.apache.tomcat.embed:tomcat-embed-core 10.0.0-M5, 9.0.35, 8.5.55; org.apache.tomcat:tomcat 10.0.0-M5, 9.0.35, 8.5.55. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.apache.tomcat.embed:tomcat-embed-core: affected >= 10.0.0-M1, <= 10.0.0-M4; >= 9.0.0.M1, < 9.0.35; >= 8.5.0, < 8.5.55; fixed in 8.5.55, 10.0.0-M5, 9.0.35
- Maven org.apache.tomcat:tomcat: affected >= 10.0.0-M1, <= 10.0.0-M4; >= 9.0.0.M1, < 9.0.35; >= 8.5.0, < 8.5.55; fixed in 8.5.55, 10.0.0-M5, 9.0.35

## Suggested inspection (read-only)
- Maven org.apache.tomcat.embed:tomcat-embed-core: check the installed version with your package manager.
- Maven org.apache.tomcat:tomcat: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.apache.tomcat.embed:tomcat-embed-core, org.apache.tomcat:tomcat.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-53hp-jpwq-2jgq (GitHub-reviewed advisory GHSA-53hp-jpwq-2jgq lists affected ranges: Maven org.apache.tomcat:tomcat >=10.0.0-M1 =9.0.0.M1 =8.5.0 =10.0.0-M1 =9.0.0.M1 =8.5.0 <8.5.55)

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