CVE-2026-34500

A vulnerability in Apache Tomcat related to improper resource shutdown or release allows for a 'made you reset' attack. This affects versions from 11.0.0-M1 to 11.0.9, from 10.1.0-M1 to 10.1.43, and from 9.0.0.M1 to 9.0.107.

The HTTP/2 implementation in Apache Tomcat from version 9.0.0.M1 to 9.0.0.M21 and from 8.5.0 to 8.5.15 bypassed several security checks that prevented directory traversal attacks. It was therefore possible to bypass security constraints using a specially crafted URL.

The HTTP/2 header parser in Apache Tomcat versions 9.0.0.M1 to 9.0.0.M11 and 8.5.0 to 8.5.6 entered an infinite loop if a header larger than the available buffer was received. This made a denial of service attack possible.

In Apache Tomcat versions 9.0.0.M1 to 9.0.0.M18 and 8.5.0 to 8.5.12, the handling of an HTTP/2 GOAWAY frame did not close streams associated with that connection waiting for a WINDOW_UPDATE, potentially leading to exhaustion of available processing threads.

The code in Apache Tomcat versions from 6.0.0 to 9.0.0.M11 allowed parsing of the HTTP request line with invalid characters. This could be exploited in conjunction with a proxy that also accepted these characters to inject data into the HTTP response.

A programming error was discovered in the processing of HTTPS requests in the Apache Tomcat servlet and JSP engine, which may result in denial of service due to an infinite loop. This issue arises from backporting the CVE-2016-6816 fix without including the fix for Tomcat bug 57544.

A buffer under-read vulnerability in Apache Tomcat means a large non-blocking write could result in the response body being split between the current request and the next request on that connection, most likely causing failure of the second request and possible leakage of data from the first response to the second.

Incorrect object recycling and reuse in Apache Tomcat affecting HTTP/2 processing of asynchronous servlets can trigger request and/or response mix-up between users. Affects versions 11.0.22 through 11.0.26, 10.1.55 through 10.1.60, and 9.0.118 through 9.0.122.

A missing critical authentication step in Apache Tomcat when the JNDI realm was configured with a non-GSSAPI SASL authentication mechanism allowed attackers to authenticate without providing the correct password. Affects versions 11.0.0-M1 through 11.0.26, 10.1.0-M1 through 10.1.60, and 9.0.0.M1 through 9.0.122; EOL versions 8.5.0-8.5.100 and 7.0.0-7.0.109 are also known to be affected.

Inconsistent interpretation of HTTP/2 requests ('HTTP Request/Response smuggling') vulnerability in Apache Tomcat caused by a regression in fix for CVE-2026-41293 can trigger request header mix-up. This issue affects Apache Tomcat: from 11.0.22 through 11.0.25, from 10.1.55 through 10.1.59, from 9.0.118 through 9.0.121. Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.