Apache Tomcat^®

This page lists all security vulnerabilities fixed in released versions of Apache Tomcat^® 11.x. Each vulnerability is given a security impact rating by the Apache Tomcat security team — please note that this rating may vary from platform to platform. We also list the versions of Apache Tomcat the flaw is known to affect, and where a flaw has not been verified list the version with a question mark.

Note: Vulnerabilities that are not Tomcat vulnerabilities but have either been incorrectly reported against Tomcat or where Tomcat provides a workaround are listed at the end of this page.

Please note that binary patches are never provided. If you need to apply a source code patch, use the building instructions for the Apache Tomcat version that you are using. For Tomcat 11.0.x those are building.html and BUILDING.txt. Both files can be found in the webapps/docs subdirectory of a binary distribution. You may also want to review the Security Considerations page in the documentation.

If you need help on building or configuring Tomcat or other help on following the instructions to mitigate the known vulnerabilities listed here, please send your questions to the public Tomcat Users mailing list

If you have encountered an unlisted security vulnerability or other unexpected behaviour that has security impact, or if the descriptions here are incomplete, please report them privately to the Tomcat Security Team. Thank you.

• Fixed in Apache Tomcat 11.0.0-M21
• Fixed in Apache Tomcat 11.0.0-M17
• Fixed in Apache Tomcat 11.0.0-M12
• Fixed in Apache Tomcat 11.0.0-M11
• Fixed in Apache Tomcat 11.0.0-M6
• Fixed in Apache Tomcat 11.0.0-M5
• Fixed in Apache Tomcat 11.0.0-M3

Important: Denial of Service CVE-2024-34750

When processing an HTTP/2 stream, Tomcat did not handle some cases of excessive HTTP headers correctly. This led to a miscounting of active HTTP/2 streams which in turn led to the use of an incorrect infinite timeout which allowed connections to remain open which should have been closed.

This was fixed with commit 2344a4c0.

This issue was reported to the Tomcat Security Team on 4 May 2024. The issue was made public on 3 July 2024.

Affects: 11.0.0-M1 to 11.0.0-M20

Important: Denial of Service CVE-2024-38286

Tomcat, under certain configurations on any platform, allows an attacker to cause an OutOfMemoryError by abusing the TLS handshake process.

This was fixed with commit 31978626.

This issue was reported to the Tomcat Security Team on 4 June 2024. The issue was made public on 23 September 2024.

Affects: 11.0.0-M1 to 11.0.0-M20

Important: Denial of Service CVE-2024-23672

It was possible for a WebSocket client to keep a WebSocket connection open leading to increased resource consumption.

This was fixed with commit b0e3b1bd.

This issue was identified by the Tomcat Security Team on 17 January 2024. The issue was made public on 13 March 2024.

Affects: 11.0.0-M1 to 11.0.0-M16

Important: Denial of Service CVE-2024-24549

When processing an HTTP/2 request, if the request exceeded any of the configured limits for headers, the associated HTTP/2 stream was not reset until after all of the headers had been processed.

This was fixed with commit 810f49d5.

This issue was reported to the Tomcat Security Team on 24 January 2024. The issue was made public on 13 March 2024.

Affects: 11.0.0-M1 to 11.0.0-M16

Important: Request smuggling CVE-2023-45648

Tomcat did not correctly parse HTTP trailer headers. A specially crafted, invalid trailer header could cause Tomcat to treat a single request as multiple requests leading to the possibility of request smuggling when behind a reverse proxy.

This was fixed with commit eb5c094e.

This issue was reported to the Tomcat Security Team on 12 September 2023. The issue was made public on 10 October 2023.

Affects: 11.0.0-M1 to 11.0.0-M11

Important: Denial of Service CVE-2023-44487

Tomcat's HTTP/2 implementation was vulnerable to the rapid reset attack. The denial of service typically manifested as an OutOfMemoryError.

This was fixed with commit 9cdfe25b.

This issue was reported to the Tomcat Security Team on 14 September 2023. The issue was made public on 10 October 2023.

Affects: 11.0.0-M1 to 11.0.0-M11

Important: Information Disclosure CVE-2023-42795

When recycling various internal objects, including the request and the response, prior to re-use by the next request/response, an error could cause Tomcat to skip some parts of the recycling process leading to information leaking from the current request/response to the next.

This was fixed with commit d6db22e4.

This issue was identified by the Tomcat Security Team on 13 September 2023. The issue was made public on 10 October 2023.

Affects: 11.0.0-M1 to 11.0.0-M11

Moderate: Open redirect CVE-2023-41080

If the ROOT (default) web application is configured to use FORM authentication then it is possible that a specially crafted URL could be used to trigger a redirect to an URL of the attackers choice.

This was fixed with commit e3703c9a.

This issue was reported to the Tomcat Security Team on 17 August 2023. The issue was made public on 22 August 2023.

Affects: 11.0.0-M1 to 11.0.0-M10

Important: Request smuggling CVE-2023-46589

Tomcat did not correctly parse HTTP trailer headers. A specially crafted trailer header that exceeded the header size limit could cause Tomcat to treat a single request as multiple requests leading to the possibility of request smuggling when behind a reverse proxy.

This was fixed with commit 6f181e10.

This issue was reported to the Tomcat Security Team on 20 October 2023. The issue was made public on 28 November 2023.

Affects: 11.0.0-M1 to 11.0.0-M10

Important: Information disclosure CVE-2023-34981

The fix for bug 66512 introduced a regression that was fixed as bug 66591. The regression meant that, if a response did not have any HTTP headers set, no AJP SEND_HEADERS message would be sent which in turn meant that at least one AJP based proxy (mod_proxy_ajp) would use the response headers from the previous request for the current request leading to an information leak.

This was fixed with commit 739c7381.

This issue was reported to the Tomcat Security Team on 24 May 2023. The issue was made public on 21 June 2023.

Affects: 11.0.0-M5

Moderate: Apache Tomcat denial of service CVE-2023-28709

The fix for CVE-2023-24998 was incomplete. If non-default HTTP connector settings were used such that the maxParameterCount could be reached using query string parameters and a request was submitted that supplied exactly maxParameterCount parameters in the query string, the limit for uploaded request parts could be bypassed with the potential for a denial of service to occur.

This was fixed with commit d53d8e7f.

This issue was reported to the Tomcat Security Team on 13 March 2023. The issue was made public on 22 May 2023.

Affects: 11.0.0-M2 to 11.0.0-M4

Important: Apache Tomcat information disclosure CVE-2023-28708

When using the RemoteIpFilter with requests received from a reverse proxy via HTTP that include the X-Forwarded-Proto header set to https, session cookies created by Tomcat did not include the secure attribute. This could result in the user agent transmitting the session cookie over an insecure channel.

This was fixed with commit c64d496d.

66471 was reported publicly on 8 February 2023. The security implications were identified by the Tomcat Security team on 9 February 2023. The issue was made public on 22 March 2023.

Affects: 11.0.0-M1 to 11.0.0-M2

Note: The issue below was fixed in Apache Tomcat 11.0.0-M2 but the release vote for the 11.0.0-M2 release candidate did not pass. Therefore, although users must download 11.0.0-M3 to obtain a version that includes a fix for these issues, version 11.0.0-M2 is not included in the list of affected versions.

Important: Apache Tomcat denial of service CVE-2023-24998

Apache Tomcat uses a packaged renamed copy of Apache Commons FileUpload to provide the file upload functionality defined in the Jakarta Servlet specification. Apache Tomcat was, therefore, also vulnerable to the Apache Commons FileUpload vulnerability CVE-2023-24998 as there was no limit to the number of request parts processed. This resulted in the possibility of an attacker triggering a DoS with a malicious upload or series of uploads.

This was fixed with commit 063e2e81.

This issue was reported to the Apache Tomcat Security team on 11 December 2022. The issue was made public on 20 February 2023.

Affects: 11.0.0-M1