GHSA-m394-8rww-3jr7

Impact

When Jetty handles a request containing request headers with a large number of “quality” (i.e. q) parameters (such as what are seen on the Accept, Accept-Encoding, and Accept-Language request headers), the server may enter a denial of service (DoS) state due to high CPU usage while sorting the list of values based on their quality values. A single request can easily consume minutes of CPU time before it is even dispatched to the application.

The only features within Jetty that can trigger this behavior are:

• Default Error Handling - the Accept request header with the QuotedQualityCSV is used to determine what kind of content to send back to the client (html, text, json, xml, etc)
• StatisticsServlet - uses the Accept request header with the QuotedQualityCSV to determine what kind of content to send back to the client (xml, json, text, html, etc)
• HttpServletRequest.getLocale() - uses the Accept-Language request header with the QuotedQualityCSV to determine which “preferred” language is returned on this call.
• HttpservletRequest.getLocales() - is similar to the above, but returns an ordered list of locales based on the quality values on the Accept-Language request header.
• DefaultServlet - uses the Accept-Encoding request header with the QuotedQualityCSV to determine which kind of pre-compressed content should be sent back for static content (content that is not matched against a url-pattern in your web app)

Versions

QuotedQualityCSV was introduced to Jetty 9.3.9.v20160517 and the bug that introduced the vulnerability was in 9.4.6.v20170531.

Currently, known vulnerable versions include:

• 9.4.6.v20170531 thru to 9.4.36.v20210114
• 10.0.0
• 11.0.0

Workarounds

Quality ordered values are used infrequently by jetty so they can be avoided by:

• Do not use the default error page/handler.
• Do not deploy the StatisticsServlet exposed to the network
• Do not call getLocale API
• Do not enable precompressed static content in the DefaultServlet

Patches

All patches are available for download from the Eclipse Jetty website at https://www.eclipse.org/jetty/download.php - 9.4.37.v20210219 and greater - 10.0.1 and greater - 11.0.1 and greater