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.

Summary

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.

Timeline

1. Jul 14, 2020, 3:00 PM UTCCVE published
2. Oct 8, 2026, 9:02 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Oct 8, 2026, 9:03 PM UTCRecord last updated
4. Oct 22, 2026EPSS reached 10%

   FIRST estimates at least a 10% chance of exploitation in the next 30 days

Affected versions

• n/a Apache Tomcat

  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, 7.0.27 to 7.0.104

• tomcatBitnami

  From 7.0.27 · fixed in 7.0.105; From 8.5.0 · fixed in 8.5.57; From 9.0.1 · fixed in 9.0.37

• org.apache.tomcat:tomcatMaven

  From 10.0.0-M1 · fixed in 10.0.0-M7

• org.apache.tomcat:tomcatMaven

  From 9.0.0.M1 · fixed in 9.0.37

• org.apache.tomcat:tomcatMaven

  From 8.5.0 · fixed in 8.5.57

• org.apache.tomcat:tomcatMaven

  From 7.0.27 · fixed in 7.0.105

• org.apache.tomcat.embed:tomcat-embed-websocketMaven

  From 7.0.27 · fixed in 7.0.105

• org.apache.tomcat.embed:tomcat-embed-websocketMaven

  From 8.5.0 · fixed in 8.5.57

• org.apache.tomcat.embed:tomcat-embed-websocketMaven

  From 9.0.0.M1 · fixed in 9.0.37

• org.apache.tomcat.embed:tomcat-embed-websocketMaven

  From 10.0.0-M1 · fixed in 10.0.0-M7

• org.apache.tomcat:tomcat-websocketMaven

  From 10.0.0-M1 · fixed in 10.0.0-M7

• org.apache.tomcat:tomcat-websocketMaven

  From 9.0.0.M1 · fixed in 9.0.37

• org.apache.tomcat:tomcat-websocketMaven

  From 8.5.0 · fixed in 8.5.57

• org.apache.tomcat:tomcat-websocketMaven

  From 7.0.27 · fixed in 7.0.105

References 17