Improper Authorization vulnerability when multiple method constraints define an HTTP method for the same extension 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 9.0.0.M1 through 9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 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 remote Ubuntu 14.04 LTS / 16.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8383-1 advisory.

    It was discovered that Tomcat incorrectly handled digest authentication. A remote attacker could possibly     use this issue to bypass authentication restrictions. (CVE-2026-43512)

    It was discovered that Tomcat incorrectly handled case sensitivity in LockOutRealm. A remote attacker     could possibly use this issue to bypass account lockout protections and obtain sensitive information.
    (CVE-2026-43513)

    It was discovered that Tomcat incorrectly handled authorization when multiple method constraints defined     the same HTTP method. A remote attacker could possibly use this issue to bypass authorization     restrictions. (CVE-2026-43515)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of Tomcat installed on the remote host is prior to 11.0.22. It is, therefore, affected by multiple vulnerabilities as referenced in the fixed_in_apache_tomcat_11.0.22_security-11 advisory.

  - DEPRECATED: Authentication Bypass Issues vulnerability in digest authentication 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 9.0.0.M1     through 9.0.117, from 8.5.0 through 8.5.100, from before 7.0.0. Older unsupported versions any also be     affect Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
    (CVE-2026-43512)

  - Improper Authorization vulnerability when multiple method constraints define an HTTP method for the same     extension 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 9.0.0.M1 through 9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 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.
    (CVE-2026-43515)

  - Observable Timing Discrepancy vulnerability when comparing AJP secret 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 9.0.0.M1 through     9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Older unsupported versions may also be     affected. Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
    (CVE-2026-43514)

  - Improper Handling of Case Sensitivity vulnerability in LockOutRealm 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 9.0.0.M1 through     9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Older unsupported versions may also be     affected. Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
    (CVE-2026-43513)

  - 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. (CVE-2026-42498)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of Apache Tomcat installed on the remote host is 9.0.0-M1 prior to 9.0.118, 10.1.0-M1 prior to 10.1.55 or 11.0.0-M1 prior to 11.0.22. It is, therefore, affected by multiple vulnerabilities :

 - When multiple security constraints defined an HTTP method constraint for the same extension pattern, only the first method constraint was applied. (CVE-2026-43515)

 - The AJP secret was compared in non-constant time allowing an attacker on the local network to mount a timing attack to determine the AJP secret. (CVE-2026-43514)

 - The LockOut Realm treated user names as case sensitive, reducing effectiveness at blocking brute force attacks against a user's password in Realms where the user name was case insensitive. (CVE-2026-43513)

 - When DIGEST authentication was configured, any user not known to the configured Realm would be authenticated if they presented the password 'null'. (CVE-2026-43512)

 - If a WebSocket request was redirected after authentication, Tomcat's WebSocket client would present the most recent authentication header to the redirect target host. (CVE-2026-42498)

 - HTTP/2 request headers were not validated, which may trigger unexpected application behavior if the application assumed header values exposed through the Servlet API would be specification compliant. (CVE-2026-41293)

 - No limit was enforced on the request body for WebDAV LOCK or PROPFIND requests available to unauthenticated users. (CVE-2026-41284)

Note that the scanner has not attempted to exploit these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Improper Authorization vulnerability when multiple method constraints define an HTTP method for the same     extension 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 9.0.0.M1 through 9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 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.
    (CVE-2026-43515)

Note that Nessus relies on the presence of the package as reported by the vendor.

The version of Tomcat installed on the remote host is prior to 10.1.55. It is, therefore, affected by multiple vulnerabilities as referenced in the fixed_in_apache_tomcat_10.1.55_security-10 advisory.

  - DEPRECATED: Authentication Bypass Issues vulnerability in digest authentication 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 9.0.0.M1     through 9.0.117, from 8.5.0 through 8.5.100, from before 7.0.0. Older unsupported versions any also be     affect Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
    (CVE-2026-43512)

  - Improper Authorization vulnerability when multiple method constraints define an HTTP method for the same     extension 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 9.0.0.M1 through 9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 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.
    (CVE-2026-43515)

  - Observable Timing Discrepancy vulnerability when comparing AJP secret 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 9.0.0.M1 through     9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Older unsupported versions may also be     affected. Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
    (CVE-2026-43514)

  - Improper Handling of Case Sensitivity vulnerability in LockOutRealm 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 9.0.0.M1 through     9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Older unsupported versions may also be     affected. Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
    (CVE-2026-43513)

  - 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. (CVE-2026-42498)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of Tomcat installed on the remote host is prior to 9.0.118. It is, therefore, affected by multiple vulnerabilities as referenced in the fixed_in_apache_tomcat_9.0.118_security-9 advisory.

  - DEPRECATED: Authentication Bypass Issues vulnerability in digest authentication 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 9.0.0.M1     through 9.0.117, from 8.5.0 through 8.5.100, from before 7.0.0. Older unsupported versions any also be     affect Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
    (CVE-2026-43512)

  - Improper Authorization vulnerability when multiple method constraints define an HTTP method for the same     extension 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 9.0.0.M1 through 9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 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.
    (CVE-2026-43515)

  - Observable Timing Discrepancy vulnerability when comparing AJP secret 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 9.0.0.M1 through     9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Older unsupported versions may also be     affected. Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
    (CVE-2026-43514)

  - Improper Handling of Case Sensitivity vulnerability in LockOutRealm 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 9.0.0.M1 through     9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Older unsupported versions may also be     affected. Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
    (CVE-2026-43513)

  - 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. (CVE-2026-42498)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
318841	Ubuntu 14.04 LTS / 16.04 LTS : Tomcat vulnerabilities (USN-8383-1)	Nessus	Ubuntu Local Security Checks	critical
316002	Apache Tomcat 11.0.0.M1 < 11.0.22 multiple vulnerabilities	Nessus	Web Servers	critical
115240	Apache Tomcat 9.0.0-M1 < 9.0.118 Multiple Vulnerabilities	Web App Scanning	Component Vulnerability	critical
115239	Apache Tomcat 10.1.0-M1 < 10.1.55 Multiple Vulnerabilities	Web App Scanning	Component Vulnerability	critical
115238	Apache Tomcat 11.0.0-M1 < 11.0.22 Multiple Vulnerabilities	Web App Scanning	Component Vulnerability	critical
314481	Linux Distros Unpatched Vulnerability : CVE-2026-43515	Nessus	Misc.	critical
314335	Apache Tomcat 10.1.0.M1 < 10.1.55 multiple vulnerabilities	Nessus	Web Servers	critical
314334	Apache Tomcat 9.0.0.M1 < 9.0.118 multiple vulnerabilities	Nessus	Web Servers	critical

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