CVE-2026-42498: Apache Tomcat Apache Tomcat - WebSocket Authentication Vulnerability

HIGH
Advisory Identifier: GHSA-fv25-8xcx-gqjc
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CVSS 7.3
CWE-200
Published
Advisory Summary

CVE-2026-42498 is a HIGH (CVSS 7.3) apache tomcat - websocket authentication vulnerability (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor) affecting Apache Tomcat libraries in the Maven ecosystem. The issue involves apache tomcat - websocket authentication header exposure. Remediation is available by upgrading affected packages to version 9.0.118, 10.1.55, 11.0.22.

CVE-2026-42498 at a Glance

CVE Identifier CVE-2026-42498
GHSA Identifier GHSA-fv25-8xcx-gqjc
Severity HIGH
CVSS v3.1 Base Score 7.3
CWE Classification CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Affected Product Apache Tomcat
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2026-42498

To remediate this vulnerability, upgrade all affected Apache Tomcat dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.apache.tomcat.embed:tomcat-embed-core fixed: 9.0.118 
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-core</artifactId>
    <version>9.0.118</version>
</dependency>
org.apache.tomcat.embed:tomcat-embed-core fixed: 10.1.55 
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-core</artifactId>
    <version>10.1.55</version>
</dependency>
org.apache.tomcat.embed:tomcat-embed-core fixed: 11.0.22 
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-core</artifactId>
    <version>11.0.22</version>
</dependency>
org.apache.tomcat:tomcat fixed: 9.0.118 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>9.0.118</version>
</dependency>
org.apache.tomcat:tomcat fixed: 10.1.55 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>10.1.55</version>
</dependency>
org.apache.tomcat:tomcat fixed: 11.0.22 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>11.0.22</version>
</dependency>
org.apache.tomcat:tomcat-catalina fixed: 9.0.118 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-catalina</artifactId>
    <version>9.0.118</version>
</dependency>
org.apache.tomcat:tomcat-catalina fixed: 10.1.55 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-catalina</artifactId>
    <version>10.1.55</version>
</dependency>
org.apache.tomcat:tomcat-catalina fixed: 11.0.22 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-catalina</artifactId>
    <version>11.0.22</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=org.apache.tomcat.embed

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-42498, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.apache.tomcat.embed

Analyze the terminal output to locate any version of Apache Tomcat in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 9.0.118), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.apache.tomcat.embed command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor, where the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. In Apache Tomcat, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Versions Affected: Apache Tomcat 11.0.0-M1 to 11.0.21 Apache Tomcat 10.1.0-M1 to 10.1.54 Apache Tomcat 9.0.2 to 9.0.117 Older, unsupported versions may also be affected Description: If a WebSocket request was redirected after authentication, Tomcat's WebSocket client would present the most recent authentication header to the redirect target host. Mitigation: Users of the affected versions should apply one of the following mitigations: - Upgrade to Apache Tomcat 11.0.22 or later - Upgrade to Apache Tomcat 10.1.55 or later - Upgrade to Apache Tomcat 9.0.118 or later Credit: This issue was identified by lokerxx

CVE-2026-42498 Affected Apache Tomcat Versions

9 component(s)
Fixed Versions:
9.0.11810.1.5511.0.22
Product / Package Ecosystem Affected Versions Fixed Version
org.apache.tomcat.embed:tomcat-embed-core
maven/org.apache.tomcat.embed/tomcat-embed-core
Maven
< 9.0.118
9.0.118
org.apache.tomcat.embed:tomcat-embed-core
maven/org.apache.tomcat.embed/tomcat-embed-core
Maven
≥ 10.1.0-M1
< 10.1.55
10.1.55
org.apache.tomcat.embed:tomcat-embed-core
maven/org.apache.tomcat.embed/tomcat-embed-core
Maven
≥ 11.0.0-M1
< 11.0.22
11.0.22
org.apache.tomcat:tomcat
maven/org.apache.tomcat/tomcat
Maven
< 9.0.118
9.0.118
org.apache.tomcat:tomcat
maven/org.apache.tomcat/tomcat
Maven
≥ 10.1.0-M1
< 10.1.55
10.1.55
org.apache.tomcat:tomcat
maven/org.apache.tomcat/tomcat
Maven
≥ 11.0.0-M1
< 11.0.22
11.0.22
org.apache.tomcat:tomcat-catalina
maven/org.apache.tomcat/tomcat-catalina
Maven
< 9.0.118
9.0.118
org.apache.tomcat:tomcat-catalina
maven/org.apache.tomcat/tomcat-catalina
Maven
≥ 10.1.0-M1
< 10.1.55
10.1.55
org.apache.tomcat:tomcat-catalina
maven/org.apache.tomcat/tomcat-catalina
Maven
≥ 11.0.0-M1
< 11.0.22
11.0.22

References

NVD — CVE-2026-42498 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42498
Security Fix Commit FIX COMMIT
https://github.com/apache/tomcat/commit/169d725788ea6aec217ecac70fe4161c837ba423
Security Fix Commit FIX COMMIT
https://github.com/apache/tomcat/commit/6cbe274592ef2d11607b5b188e1df649de52f8d5
Security Fix Commit FIX COMMIT
https://github.com/apache/tomcat/commit/b7b173694d588ddcfa432f079baf763cbbbaa5c4
Apache Tomcat Source Repository REPOSITORY
https://github.com/apache/tomcat
lists.apache.org/thread/n61zwf75jrv0... WEB
https://lists.apache.org/thread/n61zwf75jrv09rz90j4jssncm244bwdb
Apache Tomcat Security Information SECURITY
https://tomcat.apache.org/security-10.html
Apache Tomcat Security Information SECURITY
https://tomcat.apache.org/security-11.html
Apache Tomcat Security Information SECURITY
https://tomcat.apache.org/security-9.html
Apache Tomcat Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/05/12/14

Frequently Asked Questions

What is CVE-2026-42498?
CVE-2026-42498 is a security vulnerability in Apache Tomcat involving Apache Tomcat - WebSocket authentication header exposure under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.
Which Apache Tomcat versions are affected?
Affected versions include releases prior to 9.0.118, 10.1.55, 11.0.22 across affected packages: org.apache.tomcat.embed:tomcat-embed-core, org.apache.tomcat:tomcat, org.apache.tomcat:tomcat-catalina.
What version fixes CVE-2026-42498?
Upgrading to 9.0.118, 10.1.55, 11.0.22 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tomcat-embed-core affected?
Yes, org.apache.tomcat.embed:tomcat-embed-core is affected in releases prior to 9.0.118, 10.1.55, 11.0.22. Upgrade your dependency to 9.0.118, 10.1.55, 11.0.22 or later.
Is tomcat affected?
Yes, org.apache.tomcat:tomcat is affected in releases prior to 9.0.118, 10.1.55, 11.0.22. Upgrade your dependency to 9.0.118, 10.1.55, 11.0.22 or later.
What is the CVSS score of CVE-2026-42498?
CVE-2026-42498 has a CVSS v3.1 base score of 7.3 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L.
What CWE is associated with CVE-2026-42498?
CVE-2026-42498 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).
How can I check Maven dependencies for CVE-2026-42498?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.apache.tomcat.embed'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
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  "schema_version" : "1.4.0",
  "id" : "GHSA-fv25-8xcx-gqjc",
  "modified" : "2026-05-18T20:29:53Z",
  "published" : "2026-05-12T18:30:38Z",
  "aliases" : [ "CVE-2026-42498" ],
  "summary" : "Apache Tomcat - WebSocket authentication header exposure",
  "details" : "Versions Affected:\nApache Tomcat 11.0.0-M1 to 11.0.21\nApache Tomcat 10.1.0-M1 to 10.1.54\nApache Tomcat 9.0.2 to 9.0.117\nOlder, unsupported versions may also be affected\n\nDescription:\nIf a WebSocket request was redirected after authentication, Tomcat's\nWebSocket client would present the most recent authentication header to\nthe redirect target host.\n\nMitigation:\nUsers of the affected versions should apply one of the following\nmitigations:\n- Upgrade to Apache Tomcat 11.0.22 or later\n- Upgrade to Apache Tomcat 10.1.55 or later\n- Upgrade to Apache Tomcat 9.0.118 or later\n\nCredit:\nThis issue was identified by lokerxx",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.apache.tomcat.embed:tomcat-embed-core"
    },
    "ranges" : [ {
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      } ]
    } ]
  }, {
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      "name" : "org.apache.tomcat:tomcat-catalina"
    },
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    },
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        "introduced" : "11.0.0-M1"
      }, {
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      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
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  }, {
    "type" : "WEB",
    "url" : "https://github.com/apache/tomcat/commit/169d725788ea6aec217ecac70fe4161c837ba423"
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  }, {
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  }, {
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  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-18T20:29:53Z",
    "nvd_published_at" : "2026-05-12T16:16:17Z"
  }
}