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High, CVSS 7.5

Missing Release of Resource after Effective Lifetime in Apache Tomcat

CVE-2021-42340GHSA-wph7-x527-w3h5

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (org.apache.tomcat:tomcat 10.1.0-M6, 10.0.12, 9.0.54, 8.5.72), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Maven org.apache.tomcat:tomcat

    Affected
    >= 10.1.0-M1, <= 10.1.0-M5>= 10.0.0-M1, < 10.0.12>= 9.0.40, < 9.0.54>= 8.5.60, < 8.5.72
    Fixed in
    9.0.54, 10.1.0-M6, 8.5.72, 10.0.12

Sources

Severity and exploitation
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-2021-42340: 11.80% estimated exploitation activity in the next 30 days; percentile 96.09 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

The fix for bug 63362 present in Apache Tomcat 10.1.0-M1 to 10.1.0-M5, 10.0.0-M1 to 10.0.11, 9.0.40 to 9.0.53 and 8.5.60 to 8.5.71 introduced a memory leak. The object introduced to collect metrics for HTTP upgrade connections was not released for WebSocket connections once the connection was closed. This created a memory leak that, over time, could lead to a denial of service via an OutOfMemoryError.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-wph7-x527-w3h5

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2021-42340

Advisory: Missing Release of Resource after Effective Lifetime in Apache Tomcat
IDs: CVE-2021-42340, GHSA-wph7-x527-w3h5
Record: https://patchnext.com/advisories/cve-2021-42340 (revision 1, source checked 26 Oct 2026, 16:29 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 10.1.0-M6, 10.0.12, 9.0.54, 8.5.72. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.apache.tomcat:tomcat: affected >= 10.1.0-M1, <= 10.1.0-M5; >= 10.0.0-M1, < 10.0.12; >= 9.0.40, < 9.0.54; >= 8.5.60, < 8.5.72; fixed in 9.0.54, 10.1.0-M6, 8.5.72, 10.0.12

## Suggested inspection (read-only)
- 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.
- 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-wph7-x527-w3h5 (GitHub-reviewed advisory GHSA-wph7-x527-w3h5 lists affected ranges: Maven org.apache.tomcat:tomcat >=10.1.0-M1 =10.0.0-M1 =9.0.40 =8.5.60 <8.5.72)

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