CVE-2024-22201

Jetty is a Java based web server and servlet engine. An HTTP/2 SSL connection that is established and TCP congested will be leaked when it times out. An attacker can cause many connections to end up in this state, and the server may run out of file descriptors, eventually causing the server to stop accepting new connections from valid clients. The vulnerability is patched in 9.4.54, 10.0.20, 11.0.20, and 12.0.6.

Jetty is a Java based web server and servlet engine. An HTTP/2 SSL connection that is established and TCP congested will be leaked when it times out. An attacker can cause many connections to end up in this state, and the server may run out of file descriptors, eventually causing the server to stop accepting new connections from valid clients. The vulnerability is patched in 9.4.54, 10.0.20, 11.0.20, and 12.0.6.

From the reporter

XmlParser is vulnerable to XML external entity (XXE) vulnerability. XmlParser is being used when parsing Jetty’s xml configuration files. An attacker might exploit this vulnerability in order to achieve SSRF or cause a denial of service. One possible scenario is importing a (remote) malicious WAR into a Jetty’s server, while the WAR includes a malicious web.xml.

Impact

There are no circumstances in a normally deployed Jetty server where potentially hostile XML is given to the XmlParser class without the attacker already having arbitrary access to the server. I.e. in order to exploit XmlParser the attacker would already have the ability to deploy and execute hostile code. Specifically, Jetty has no protection against malicious web application and potentially hostile web applications should only be run on an isolated virtualisation.

Thus this is not considered a vulnerability of the Jetty server itself, as any such usage of the jetty XmlParser is equally vulnerable as a direct usage of the JVM supplied SAX parser. No CVE will be allocated to this advisory.

However, any direct usage of the XmlParser class by an application may be vulnerable. The impact would greatly depend on how the application uses XmlParser, but it could be a denial of service due to large entity expansion, or possibly the revealing local files if the XML results are accessible remotely.

Patches

Ability to configure the SAXParserFactory to fit the needs of your particular XML parser implementation have been merged as part of PR #10067

Workarounds

Don't use Jetty's XmlParser to parse data from users.

Impact

If an HTTP/2 connection gets TCP congested, when an idle timeout occurs the HTTP/2 session is marked as closed, and then a GOAWAY frame is queued to be written. However it is not written because the connection is TCP congested. When another idle timeout period elapses, it is then supposed to hard close the connection, but it delegates to the HTTP/2 session which reports that it has already been closed so it does not attempt to hard close the connection.

This leaves the connection in ESTABLISHED state (i.e. not closed), TCP congested, and idle.

An attacker can cause many connections to end up in this state, and the server may run out of file descriptors, eventually causing the server to stop accepting new connections from valid clients.

The client may also be impacted (if the server does not read causing a TCP congestion), but the issue is more severe for servers.

Patches

Patched versions:

• 9.4.54
• 10.0.20
• 11.0.20
• 12.0.6

Workarounds

Disable HTTP/2 and HTTP/3 support until you can upgrade to a patched version of Jetty. HTTP/1.x is not affected.

References

• https://github.com/jetty/jetty.project/issues/11256.

Jetty is a Java based web server and servlet engine. An HTTP/2 SSL connection that is established and TCP congested will be leaked when it times out. An attacker can cause many connections to end up in this state, and the server may run out of file descriptors, eventually causing the server to stop accepting new connections from valid clients. The vulnerability is patched in 9.4.54, 10.0.20, 11.0.20, and 12.0.6.

Jetty is a Java based web server and servlet engine. An HTTP/2 SSL connection that is established and TCP congested will be leaked when it times out. An attacker can cause many connections to end up in this state, and the server may run out of file descriptors, eventually causing the server to stop accepting new connections from valid clients. The vulnerability is patched in 9.4.54, 10.0.20, 11.0.20, and 12.0.6.