In Apache Tomcat there is an improper handing of overflow in the UTF-8 decoder

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-2018-1336: 20.35% estimated exploitation activity in the next 30 days; percentile 97.49 (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 improper handing of overflow in the UTF-8 decoder with supplementary characters can lead to an infinite loop in the decoder causing a Denial of Service. Versions Affected: Apache Tomcat 9.0.0.M9 to 9.0.7, 8.5.0 to 8.5.30, 8.0.0.RC1 to 8.0.51, and 7.0.28 to 7.0.86.

Published by the source

17 Oct 2018, 16:32 UTC

Last modified by the source

23 Feb 2024, 17:57 UTC

Source last checked

26 Oct 2026, 16:26 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-m59c-jpc8-m2x4

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# Patch Next advisory brief: CVE-2018-1336

Advisory: In Apache Tomcat there is an improper handing of overflow in the UTF-8 decoder
IDs: CVE-2018-1336, GHSA-m59c-jpc8-m2x4
Record: https://patchnext.com/advisories/cve-2018-1336 (revision 1, source checked 26 Oct 2026, 16:26 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 9.0.8, 8.5.31, 8.0.51, 7.0.87. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.apache.tomcat.embed:tomcat-embed-core: affected >= 8.5.0, < 8.5.31; >= 7.0.28, < 7.0.87; >= 9.0.0.M9, <= 9.0.7; >= 8.0.0RC1, < 8.0.51; fixed in 8.5.31, 7.0.87, 9.0.8, 8.0.51

## 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?
- 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-m59c-jpc8-m2x4 (GitHub-reviewed advisory GHSA-m59c-jpc8-m2x4 lists affected ranges: Maven org.apache.tomcat.embed:tomcat-embed-core >=8.5.0 =7.0.28 =9.0.0.M9 =8.0.0RC1 <8.0.51)

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