Improper Privilege Management in Tomcat

Exploitation

Confirmed: listed in the CISA Known Exploited Vulnerabilities catalog.

CVSS

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

EPSS

• CVE-2020-1938: 99.27% estimated exploitation activity in the next 30 days; percentile 99.94 (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.

When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache Tomcat. Tomcat treats AJP connections as having higher trust than, for example, a similar HTTP connection. If such connections are available to an attacker, they can be exploited in ways that may be surprising. In Apache Tomcat 9.0.0.M1 to 9.0.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99, Tomcat shipped with an AJP Connector enabled by default that listened on all configured IP addresses. It was expected (and recommended in the security guide) that this Connector would be disabled if not required. This vulnerability report identified a mechanism that allowed: returning arbitrary files from anywhere in the web application, processing any file in the web application as a JSP Further, if the web application allowed file upload and stored those files within the web application (or the attacker was able to control the content of the web application by some other means) then this, along…

Published by the source

15 Jun 2020, 18:51 UTC

Last modified by the source

22 Oct 2025, 17:46 UTC

Source last checked

26 Oct 2026, 16:40 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-c9hw-wf7x-jp9j

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

# Patch Next advisory brief: CVE-2020-1938

Advisory: Improper Privilege Management in Tomcat
IDs: CVE-2020-1938, GHSA-c9hw-wf7x-jp9j
Record: https://patchnext.com/advisories/cve-2020-1938 (revision 1, source checked 26 Oct 2026, 16:40 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: confirmed: listed in the CISA Known Exploited Vulnerabilities catalog.
Vendor response: Vendor fix available; fixed versions by package: org.apache.tomcat.embed:tomcat-embed-core 9.0.31, 8.5.51, 7.0.100. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.apache.tomcat.embed:tomcat-embed-core: affected >= 9.0.0, < 9.0.31; >= 8.0.0, < 8.5.51; >= 7.0.0, < 7.0.100; fixed in 9.0.31, 8.5.51, 7.0.100

## Suggested inspection (read-only)
- Maven org.apache.tomcat.embed:tomcat-embed-core: 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.
- 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?
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://www.cisa.gov/known-exploited-vulnerabilities-catalog (CISA added CVE-2020-1938 to the Known Exploited Vulnerabilities catalog on 2022-03-03.)
- Verified: https://github.com/advisories/GHSA-c9hw-wf7x-jp9j (GitHub-reviewed advisory GHSA-c9hw-wf7x-jp9j lists affected ranges: Maven org.apache.tomcat.embed:tomcat-embed-core >=9.0.0 =8.0.0 =7.0.0 <7.0.100)

Commands are suggestions: review each one before running it.