Improper Restriction of Operations within the Bounds of a Memory Buffer 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-2020-13934: 64.12% estimated exploitation activity in the next 30 days; percentile 99.23 (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.

An h2c direct connection to Apache Tomcat 10.0.0-M1 to 10.0.0-M6, 9.0.0.M5 to 9.0.36 and 8.5.1 to 8.5.56 did not release the HTTP/1.1 processor after the upgrade to HTTP/2. If a sufficient number of such requests were made, an OutOfMemoryException could occur leading to a denial of service.

Published by the source

8 Feb 2022, 22:05 UTC

Last modified by the source

20 May 2026, 18:50 UTC

Source last checked

26 Oct 2026, 16:45 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-vf77-8h7g-gghp

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# Patch Next advisory brief: CVE-2020-13934

Advisory: Improper Restriction of Operations within the Bounds of a Memory Buffer in Apache Tomcat
IDs: CVE-2020-13934, GHSA-vf77-8h7g-gghp
Record: https://patchnext.com/advisories/cve-2020-13934 (revision 1, source checked 26 Oct 2026, 16:45 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:tomcat-coyote 10.0.0-M6, 9.0.36, 8.5.56; org.apache.tomcat:tomcat 10.0.0-M6, 9.0.36, 8.5.56. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.apache.tomcat:tomcat-coyote: affected >= 10.0.0-M1, <= 10.0.0-M5; >= 9.0.0.M5, < 9.0.36; >= 8.5.1, < 8.5.56; fixed in 9.0.36, 8.5.56, 10.0.0-M6
- Maven org.apache.tomcat:tomcat: affected >= 10.0.0-M1, <= 10.0.0-M5; >= 9.0.0.M5, < 9.0.36; >= 8.5.1, < 8.5.56; fixed in 9.0.36, 8.5.56, 10.0.0-M6

## Suggested inspection (read-only)
- Maven org.apache.tomcat:tomcat-coyote: 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:tomcat-coyote, 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-vf77-8h7g-gghp (GitHub-reviewed advisory GHSA-vf77-8h7g-gghp lists affected ranges: Maven org.apache.tomcat:tomcat >=10.0.0-M1 =9.0.0.M5 =8.5.1 =10.0.0-M1 =9.0.0.M5 =8.5.1 <8.5.56)

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