# CVE-2020-13935: libtomcat9-embed-java: The payload length in a WebSocket frame was not correctly validated in Apache Tomcat 10.0.0-M1 to 10.0.0-M6, 9.0.0.M1...

CVE-2020-13935 is fixed in 8 products on 1 platform, first by libtomcat9-embed-java 9.0.31-1ubuntu0.1, released July 14, 2020. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2020-13935
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.8661
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 14, 2020

## Description

The payload length in a WebSocket frame was not correctly validated in Apache Tomcat 10.0.0-M1 to 10.0.0-M6, 9.0.0.M1 to 9.0.36, 8.5.0 to 8.5.56 and 7.0.27 to 7.0.104. Invalid payload lengths could trigger an infinite loop. Multiple requests with invalid payload lengths could lead to a denial of service.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libtomcat9-embed-java Ubuntu 20.04 LTS (focal) | 9.0.31-1ubuntu0.1 | [libtomcat9-embed-java 9.0.31-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libtomcat9-embed-java-9.0.31-1ubuntu0.1.md) | Jul 14, 2020 |
| Linux | libtomcat9-java Ubuntu 20.04 LTS (focal) | 9.0.31-1ubuntu0.1 | [libtomcat9-java 9.0.31-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libtomcat9-java-9.0.31-1ubuntu0.1.md) | Jul 14, 2020 |
| Linux | tomcat9 Ubuntu 20.04 LTS (focal) | 9.0.31-1ubuntu0.1 | [tomcat9 9.0.31-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-tomcat9-9.0.31-1ubuntu0.1.md) | Jul 14, 2020 |
| Linux | tomcat9-admin Ubuntu 20.04 LTS (focal) | 9.0.31-1ubuntu0.1 | [tomcat9-admin 9.0.31-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-tomcat9-admin-9.0.31-1ubuntu0.1.md) | Jul 14, 2020 |
| Linux | tomcat9-common Ubuntu 20.04 LTS (focal) | 9.0.31-1ubuntu0.1 | [tomcat9-common 9.0.31-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-tomcat9-common-9.0.31-1ubuntu0.1.md) | Jul 14, 2020 |
| Linux | tomcat9-docs Ubuntu 20.04 LTS (focal) | 9.0.31-1ubuntu0.1 | [tomcat9-docs 9.0.31-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-tomcat9-docs-9.0.31-1ubuntu0.1.md) | Jul 14, 2020 |
| Linux | tomcat9-examples Ubuntu 20.04 LTS (focal) | 9.0.31-1ubuntu0.1 | [tomcat9-examples 9.0.31-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-tomcat9-examples-9.0.31-1ubuntu0.1.md) | Jul 14, 2020 |
| Linux | tomcat9-user Ubuntu 20.04 LTS (focal) | 9.0.31-1ubuntu0.1 | [tomcat9-user 9.0.31-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-tomcat9-user-9.0.31-1ubuntu0.1.md) | Jul 14, 2020 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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