CVE-2024-1635
HighCVSS 7.5Exploitation Probability (EPSS)
Very high risk91th percentile - higher than 91% of all known CVEs
Summary
A vulnerability was found in Undertow that impacts a server supporting the wildfly-http-client protocol. When a malicious user opens and closes a connection with the HTTP port and then closes it immediately, the server may exhaust memory and open file limits. During HTTP upgrade to remoting, WriteTimeoutStreamSinkConduit leaks connections if RemotingConnection is closed by Remoting ServerConnectionOpenListener, leading to a leak of the entire dependency tree.
Risk Assessment
The risk includes the possibility of resource exhaustion (denial of service) via specially crafted requests, which could disrupt service availability.
Recommendation
It is recommended to update Undertow to a patched version and monitor memory usage and open file counts on the server.
Original NVD description (English source)
A vulnerability was found in Undertow. This vulnerability impacts a server that supports the wildfly-http-client protocol. Whenever a malicious user opens and closes a connection with the HTTP port of the server and then closes the connection immediately, the server will end with both memory and open file limits exhausted at some point, depending on the amount of memory available. At HTTP upgrade to remoting, the WriteTimeoutStreamSinkConduit leaks connections if RemotingConnection is closed by Remoting ServerConnectionOpenListener. Because the remoting connection originates in Undertow as part of the HTTP upgrade, there is an external layer to the remoting connection. This connection is unaware of the outermost layer when closing the connection during the connection opening procedure. Hence, the Undertow WriteTimeoutStreamSinkConduit is not notified of the closed connection in this scenario. Because WriteTimeoutStreamSinkConduit creates a timeout task, the whole dependency tree leaks via that task, which is added to XNIO WorkerThread. So, the workerThread points to the Undertow conduit, which contains the connections and causes the leak.