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.

Apache Tomcat contains an unspecified vulnerability that allows for remote code execution if JmxRemoteLifecycleListener is used and an attacker can reach Java Management Extension (JMX) ports. This CVE exists because this listener wasn't updated for consistency with the Oracle patched issues for CVE-2016-3427 which affected credential types.

Apache Tomcat could allow a remote attacker to execute arbitrary code on the system, caused by a file read/inclusion vulnerability in the AJP connector. By sending a specially-crafted request, an attacker could exploit this vulnerability to read web application files from a vulnerable server and upload malicious JavaServer Pages (JSP) code within a variety of file types and execute arbitrary code on the system.

Note: This vulnerability is known as Ghostcat.

Last updated 25 August 2025

Last updated 2 August 2024

A flaw was found in Apache Tomcat. When responding to new h2c connection requests, Apache Tomcat could duplicate request headers and a limited amount of request body from one request to another meaning user A and user B could both see the results of user A's request. The highest threat from this vulnerability is to data confidentiality.

Apache Tomcat could allow a remote attacker to bypass security restrictions, caused by improper error handling in WebSocket connection. By sending a specially-crafted WebSocket message concurrently with the WebSocket connection closing, an attacker could exploit this vulnerability to continue to use the socket after it has been closed.

Improper Handling of Case Sensitivity vulnerability in LockOutRealm in Apache Tomcat.

Improper Authorization vulnerability when multiple method constraints define an HTTP method for the same extension in Apache Tomcat.

DEPRECATED: Authentication Bypass Issues vulnerability in digest authentication in Apache Tomcat.

Exposure of HTTP Authentication Header to unexpected hosts during WebSocket authentication vulnerability in Apache Tomcat.

HTTP/2 Rapid reset attack The HTTP/2 protocol allows clients to indicate to the server that a previous stream should be canceled by sending a RSTSTREAM frame. The protocol does not require the client and server to coordinate the cancellation in any way, the client may do it unilaterally. The client may also assume that the cancellation will take effect immediately when the server receives the RSTSTREAM frame, before any other data from that TCP connection is processed.

Abuse of this feature is called a Rapid Reset attack because it relies on the ability for an endpoint to send a RSTSTREAM frame immediately after sending a request frame, which makes the other endpoint start working and then rapidly resets the request. The request is canceled, but leaves the HTTP/2 connection open.

The HTTP/2 Rapid Reset attack built on this capability is simple: The client opens a large number of streams at once as in the standard HTTP/2 attack, but rather than waiting for a response to each request stream from the server or proxy, the client cancels each request immediately.

The ability to reset streams immediately allows each connection to have an indefinite number of requests in flight. By explicitly canceling the requests, the attacker never exceeds the limit on the number of concurrent open streams. The number of in-flight requests is no longer dependent on the round-trip time (RTT), but only on the available network bandwidth.

In a typical HTTP/2 server implementation, the server will still have to do significant amounts of work for canceled requests, such as allocating new stream data structures, parsing the query and doing header decompression, and mapping the URL to a resource. For reverse proxy implementations, the request may be proxied to the backend server before the RSTSTREAM frame is processed. The client on the other hand paid almost no costs for sending the requests. This creates an exploitable cost asymmetry between the server and the client.

Multiple software artifacts implementing HTTP/2 are affected. This advisory was originally ingested from the swift-nio-http2 repo advisory and their original conent follows.

swift-nio-http2 specific advisory swift-nio-http2 is vulnerable to a denial-of-service vulnerability in which a malicious client can create and then reset a large number of HTTP/2 streams in a short period of time. This causes swift-nio-http2 to commit to a large amount of expensive work which it then throws away, including creating entirely new Channels to serve the traffic. This can easily overwhelm an EventLoop and prevent it from making forward progress.

swift-nio-http2 1.28 contains a remediation for this issue that applies reset counter using a sliding window. This constrains the number of stream resets that may occur in a given window of time. Clients violating this limit will have their connections torn down. This allows clients to continue to cancel streams for legitimate reasons, while constraining malicious actors.

Improper Handling of URL Encoding (Hex Encoding) vulnerability in Apache Tomcat's rewrite valve allowed security constraint bypass for some configurations.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.23, from 10.1.0-M1 through 10.1.56, from 9.0.0.M1 through 9.0.119, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected.

Users are recommended to upgrade to version 11.0.24, 10.1.57 or 9.0.120, which fix the issue.

Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat's rewrite valve meant that if the first condition in an OR chain matched, subsequent non-OR conditions were skipped.

Apache Tomcat is vulnerable to HTTP request smuggling, caused by the failure to reject a request containing an invalid Content-Length header when configured to ignore invalid HTTP headers via setting rejectIllegalHeader to false. By sending a specially-crafted request, an attacker could exploit this vulnerability to poison the web cache, bypass web application firewall protection, and conduct XSS attacks.

Flaw affecting tomcat 9.0.0.M9 to 9.0.9 and 8.5.5 to 8.5.31. A bug in the tracking of connection closures can lead to reuse of user sessions in a new connection.

Upstream patch:

http://svn.apache.org/viewvc?view=rev&rev=1833906 http://svn.apache.org/viewvc?view=rev&rev=1833907

References:

https://tomcat.apache.org/security-8.html https://tomcat.apache.org/security-9.html

Unchecked Error Condition vulnerability in Apache Tomcat. If Tomcat is configured to use a custom Jakarta Authentication (formerly JASPIC) ServerAuthContext component which may throw an exception during the authentication process without explicitly setting an HTTP status to indicate failure, the authentication may not fail, allowing the user to bypass the authentication process. There are no known Jakarta Authentication components that behave in this way.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.0-M26, from 10.1.0-M1 through 10.1.30, from 9.0.0-M1 through 9.0.95.

The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 though 8.5.100. Other EOL versions may also be affected.

Users are recommended to upgrade to version 11.0.0, 10.1.31 or 9.0.96, which fix the issue.

Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability during JSP compilation in Apache Tomcat permits an RCE on case insensitive file systems when the default servlet is enabled for write (non-default configuration).

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.1, from 10.1.0-M1 through 10.1.33, from 9.0.0.M1 through 9.0.97.

The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 though 8.5.100. Other, older, EOL versions may also be affected.

Users are recommended to upgrade to version 11.0.2, 10.1.34 or 9.0.98, which fixes the issue.

Uncontrolled Resource Consumption vulnerability in the examples web application provided with Apache Tomcat leads to denial of service.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.1, from 10.1.0-M1 through 10.1.33, from 9.0.0.M1 through 9.9.97.

Users are recommended to upgrade to version 11.0.2, 10.1.34 or 9.0.98, which fixes the issue.

Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in Apache Tomcat.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.1, from 10.1.0-M1 through 10.1.33, from 9.0.0.M1 through 9.0.97.

The mitigation for CVE-2024-50379 was incomplete.

Users running Tomcat on a case insensitive file system with the default servlet write enabled (readonly initialisation parameter set to the non-default value of false) may need additional configuration to fully mitigate CVE-2024-50379 depending on which version of Java they are using with Tomcat: - running on Java 8 or Java 11: the system property sun.io.useCanonCaches must be explicitly set to false (it defaults to true) - running on Java 17: the system property sun.io.useCanonCaches, if set, must be set to false (it defaults to false) - running on Java 21 onwards: no further configuration is required (the system property and the problematic cache have been removed)

Tomcat 11.0.3, 10.1.35 and 9.0.99 onwards will include checks that sun.io.useCanonCaches is set appropriately before allowing the default servlet to be write enabled on a case insensitive file system. Tomcat will also set sun.io.useCanonCaches to false by default where it can.

Denial of Service due to improper input validation vulnerability for HTTP/2 requests in Apache Tomcat. 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 issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.0-M16, from 10.1.0-M1 through 10.1.18, from 9.0.0-M1 through 9.0.85, from 8.5.0 through 8.5.98.

Users are recommended to upgrade to version 11.0.0-M17, 10.1.19, 9.0.86 or 8.5.99 which fix the issue.

Denial of Service via incomplete cleanup vulnerability in Apache Tomcat. It was possible for WebSocket clients to keep WebSocket connections open leading to increased resource consumption.This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.0-M16, from 10.1.0-M1 through 10.1.18, from 9.0.0-M1 through 9.0.85, from 8.5.0 through 8.5.98.

Older, EOL versions may also be affected.

Users are recommended to upgrade to version 11.0.0-M17, 10.1.19, 9.0.86 or 8.5.99 which fix the issue.

A flaw was found in Apache tomcat. When the default servlet returned a redirect to a directory (e.g. redirecting to /foo/ when the user requested /foo) a specially crafted URL could be used to cause the redirect to be generated to any URI of the attackers choice.

References:

https://lists.apache.org/thread.html/23134c9b5a23892a205dc140cdd8c9c0add233600f76b313dda6bd75@%3Cannounce.tomcat.apache.org%3E

Affected versions:

- Apache Tomcat 11.0.0-M1 through 11.0.0-M10 - Apache Tomcat 10.1.0-M1 through 10.1.15 - Apache Tomcat 9.0.0-M1 through 9.0.82 - Apache Tomcat 8.5.0 through 8.5.95

Description:

Improper Input Validation vulnerability in Apache Tomcat.Tomcat from 11.0.0-M1 through 11.0.0-M10, from 10.1.0-M1 through 10.1.15, from 9.0.0-M1 through 9.0.82 and from 8.5.0 through 8.5.95 did not correctly parse HTTP trailer headers. A 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.

Users are recommended to upgrade to version 11.0.0-M11 onwards, 10.1.16 onwards, 9.0.83 onwards or 8.5.96 onwards, which fix the issue.

Credit:

Norihito Aimoto (OSSTech Corporation) (finder)

References:

https://lists.apache.org/thread/0rqq6ktozqc42ro8hhxdmmdjm1k1tpxr http://www.openwall.com/lists/oss-security/2023/11/28/2

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.

https://lists.apache.org/thread/71wvwprtx2j2m54fovq9zr7gbm2wow2f https://github.com/advisories/GHSA-q3mw-pvr8-9ggc

Allocation of Resources Without Limits or Throttling vulnerability in Apache Tomcat.

Improper Input Validation vulnerability in Apache Tomcat.

Improper Handling of Exceptional Conditions, Uncontrolled Resource Consumption vulnerability in Apache Tomcat. 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 issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.0-M20, from 10.1.0-M1 through 10.1.24, from 9.0.0-M1 through 9.0.89.

The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 though 8.5.100. Other EOL versions may also be affected.

Users are recommended to upgrade to version 11.0.0-M21, 10.1.25 or 9.0.90, which fixes the issue.

Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in Apache Tomcat. For a subset of unlikely rewrite rule configurations, it was possible for a specially crafted request to bypass some rewrite rules. If those rewrite rules effectively enforced security constraints, those constraints could be bypassed.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.5, from 10.1.0-M1 through 10.1.39, from 9.0.0.M1 through 9.0.102.

Users are recommended to upgrade to version [FIXEDVERSION], which fixes the issue.

Improper Handling of Case Sensitivity vulnerability in Apache Tomcat's GCI servlet allows security constraint bypass of security constraints that apply to the pathInfo component of a URI mapped to the CGI servlet.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.6, from 10.1.0-M1 through 10.1.40, from 9.0.0.M1 through 9.0.104.

Users are recommended to upgrade to version 11.0.7, 10.1.41 or 9.0.105, which fixes the issue.