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Infinite Loop in Apache Tomcat

High severity GitHub Reviewed Published Feb 8, 2022 to the GitHub Advisory Database • Updated Aug 25, 2026

Package

maven org.apache.tomcat.embed:tomcat-embed-websocket (Maven)

Affected versions

>= 7.0.27, < 7.0.105
>= 8.5.0, < 8.5.57
>= 9.0.0.M1, < 9.0.37
>= 10.0.0-M1, < 10.0.0-M7

Patched versions

7.0.105
8.5.57
9.0.37
10.0.0-M7
maven org.apache.tomcat:tomcat (Maven)
>= 10.0.0-M1, < 10.0.0-M7
>= 9.0.0.M1, < 9.0.37
>= 8.5.0, < 8.5.57
>= 7.0.27, < 7.0.105
10.0.0-M7
9.0.37
8.5.57
7.0.105
maven org.apache.tomcat:tomcat-websocket (Maven)
>= 10.0.0-M1, < 10.0.0-M7
>= 9.0.0.M1, < 9.0.37
>= 8.5.0, < 8.5.57
>= 7.0.27, < 7.0.105
10.0.0-M7
9.0.37
8.5.57
7.0.105

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.

References

Published by the National Vulnerability Database Jul 14, 2020
Reviewed Apr 12, 2021
Published to the GitHub Advisory Database Feb 8, 2022
Last updated Aug 25, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(100th percentile)

Weaknesses

Loop with Unreachable Exit Condition ('Infinite Loop')

The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. Learn more on MITRE.

CVE ID

CVE-2020-13935

GHSA ID

GHSA-m7jv-hq7h-mq7c

Source code

Credits

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