Apache Tomcat up to 11.0.21 WebSocket Authentication information disclosure

Summaryinfo

A vulnerability categorized as problematic has been discovered in Apache Tomcat up to 7.0.109/8.5.100/9.0.117/10.1.54/11.0.21. Affected by this issue is some unknown functionality of the component WebSocket Authentication. Such manipulation leads to information disclosure. This vulnerability is documented as CVE-2026-42498. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Apache Tomcat up to 7.0.109/8.5.100/9.0.117/10.1.54/11.0.21 and classified as problematic. Affected by this issue is an unknown functionality of the component WebSocket Authentication. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. CVE summarizes:

Exposure of HTTP Authentication Header to unexpected hosts during WebSocket authentication vulnerability in Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.21, from 10.1.0-M1 through 10.1.54, from 9.0.2 through 9.0.117, from 8.5.24 through 8.5.100, from 7.0.83 through 7.0.109. Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118, which fix the issue.

The weakness was released by lokerxx. The advisory is shared for download at lists.apache.org. This vulnerability is handled as CVE-2026-42498 since 04/28/2026. The exploitation is known to be easy. The attack may be launched remotely. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 05/13/2026). The MITRE ATT&CK project declares the attack technique as T1592.

The vulnerability scanner Nessus provides a plugin with the ID 314335 (Apache Tomcat 10.1.0.M1 < 10.1.55 multiple vulnerabilities), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 9.0.118, 10.1.55 or 11.0.22 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (314335). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Application Server Software

Vendor

• Apache

Name

• Tomcat

Version

• 7.0.109
• 8.0
• 8.1
• 8.2
• 8.3
• 8.4
• 8.5.100
• 9.0.117
• 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
• 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

License

• open-source

Website

• Vendor: https://www.apache.org/

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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