Description There exists a security vulnerability in Jetty's DosFilter which can be exploited by unauthorized users to cause remote denial-of-service (DoS) attack on the server using DosFilter. By repeatedly sending crafted requests, attackers can trigger OutofMemory errors and exhaust the server's memory finally.

Vulnerability details The Jetty DoSFilter (Denial of Service Filter) is a security filter designed to protect web applications against certain types of Denial of Service (DoS) attacks and other abusive behavior. It helps to mitigate excessive resource consumption by limiting the rate at which clients can make requests to the server. The DoSFilter monitors and tracks client request patterns, including request rates, and can take actions such as blocking or delaying requests from clients that exceed predefined thresholds. The internal tracking of requests in DoSFilter is the source of this OutOfMemory condition.

Impact Users of the DoSFilter may be subject to DoS attacks that will ultimately exhaust the memory of the server if they have not configured session passivation or an aggressive session inactivation timeout.

Patches The DoSFilter has been patched in all active releases to no longer support the session tracking mode, even if configured.

Patched releases:

9.4.54 10.0.18 11.0.18 12.0.3

Impact

Jetty accepts the '+' character proceeding the content-length value in a HTTP/1 header field. This is more permissive than allowed by the RFC and other servers routinely reject such requests with 400 responses. There is no known exploit scenario, but it is conceivable that request smuggling could result if jetty is used in combination with a server that does not close the connection after sending such a 400 response.

Workarounds

There is no workaround as there is no known exploit scenario.

Original Report

RFC 9110 Secion 8.6 defined the value of Content-Length header should be a string of 0-9 digits. However we found that Jetty accepts "+" prefixed Content-Length, which could lead to potential HTTP request smuggling.

Payload:

POST / HTTP/1.1 Host: a.com Content-Length: +16 Connection: close ​ 0123456789abcdef

When sending this payload to Jetty, it can successfully parse and identify the length.

When sending this payload to NGINX, Apache HTTPd or other HTTP servers/parsers, they will return 400 bad request.

This behavior can lead to HTTP request smuggling and can be leveraged to bypass WAF or IDS.

Eclipse Jetty Canonical Repository is the canonical repository for the Jetty project. Users of the CgiServlet with a very specific command structure may have the wrong command executed. If a user sends a request to a org.eclipse.jetty.servlets.CGI Servlet for a binary with a space in its name, the servlet will escape the command by wrapping it in quotation marks. This wrapped command, plus an optional command prefix, will then be executed through a call to Runtime.exec. If the original binary name provided by the user contains a quotation mark followed by a space, the resulting command line will contain multiple tokens instead of one. This issue was patched in version 9.4.52, 10.0.16, 11.0.16 and 12.0.0-beta2.