CVE-2023-53296: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53296 is a vulnerability discovered in the Linux kernel affecting the SCTP (Stream Control Transmission Protocol) implementation. The vulnerability was disclosed on September 16, 2025, and involves a corner case in stream number handling after wait_for_sndbuf operation (NVD).

The vulnerability occurs when the asoc out stream count may change after wait_for_sndbuf. Specifically, when the main thread in the client starts a connection with out stream count N while the server's in stream count is N-2, another thread in the client sending messages with stream number N-1 and waiting for sndbuf before processing INIT_ACK can trigger a crash. After processing INIT_ACK, the client's out stream count is reduced to N-2, matching the server's in stream count. The crash manifests as a null pointer dereference when attempting to send a message in a non-existing stream (NVD).

The vulnerability can lead to a system crash due to null pointer dereference when attempting to access non-existing streams in the SCTP implementation. This could potentially affect system stability and availability in environments where SCTP is actively used (NVD).

A fix has been implemented that adds an unlikely check for the send stream number after the thread wakes up from the wait_for_sndbuf operation. This patch has been integrated into the Linux kernel to prevent the null pointer dereference condition (NVD).