Apache Tomcat up to 9.0.120/10.1.57/11.0.24 WebSocket Chat Example resource consumption

Summaryinfo

A vulnerability was found in Apache Tomcat up to 9.0.120/10.1.57/11.0.24. It has been rated as problematic. This impacts an unknown function of the component WebSocket Chat Example. This manipulation causes resource consumption. This vulnerability is tracked as CVE-2026-66299. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability classified as problematic was found in Apache Tomcat up to 9.0.120/10.1.57/11.0.24. Affected by this vulnerability is an unknown function of the component WebSocket Chat Example. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. The summary by CVE is:

Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example. This issue affects Apache Tomcat: from 11.0.0-M20 through 11.0.24, from 10.1.24 through 10.1.57, from 9.0.89 through 9.0.120. Users who have followed the security guidance to remove the examples web application are not affected by this issue. Users are recommended to remove the examples web application or to upgrade to version 11.0.25, 10.1.58 or 9.0.121 (when released), which fix the issue.

It is possible to read the advisory at lists.apache.org. This vulnerability is known as CVE-2026-66299 since 07/24/2026. The exploitation appears to be easy. The attack can be launched remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/28/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 9.0.121, 10.1.58 or 11.0.25 eliminates this vulnerability.

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Productinfo

Type

• Application Server Software

Vendor

• Apache

Name

• Tomcat

Version

• 9.0.120
• 10.1.0
• 10.1.1
• 10.1.2
• 10.1.3
• 10.1.4
• 10.1.5
• 10.1.6
• 10.1.7
• 10.1.8
• 10.1.9
• 10.1.10
• 10.1.11
• 10.1.12
• 10.1.13
• 10.1.14
• 10.1.15
• 10.1.16
• 10.1.17
• 10.1.18
• 10.1.19
• 10.1.20
• 10.1.21
• 10.1.22
• 10.1.23
• 10.1.24
• 10.1.25
• 10.1.26
• 10.1.27
• 10.1.28
• 10.1.29
• 10.1.30
• 10.1.31
• 10.1.32
• 10.1.33
• 10.1.34
• 10.1.35
• 10.1.36
• 10.1.37
• 10.1.38
• 10.1.39
• 10.1.40
• 10.1.41
• 10.1.42
• 10.1.43
• 10.1.44
• 10.1.45
• 10.1.46
• 10.1.47
• 10.1.48
• 10.1.49
• 10.1.50
• 10.1.51
• 10.1.52
• 10.1.53
• 10.1.54
• 10.1.55
• 10.1.56
• 10.1.57
• 11.0.0
• 11.0.1
• 11.0.2
• 11.0.3
• 11.0.4
• 11.0.5
• 11.0.6
• 11.0.7
• 11.0.8
• 11.0.9
• 11.0.10
• 11.0.11
• 11.0.12
• 11.0.13
• 11.0.14
• 11.0.15
• 11.0.16
• 11.0.17
• 11.0.18
• 11.0.19
• 11.0.20
• 11.0.21
• 11.0.22
• 11.0.23
• 11.0.24

License

• open-source

Website

• Vendor: https://www.apache.org/

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