CVE-2023-53296: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.1% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: sctp: check send stream number after wait_for_sndbuf This patch fixes a corner case where the asoc out stream count may change after wait_for_sndbuf. When the main thread in the client starts a connection, if its out stream count is set to N while the in stream count in the server is set to N - 2, another thread in the client keeps sending the msgs with stream number N - 1, and waits for sndbuf before processing INIT_ACK. However, after processing INIT_ACK, the out stream count in the client is shrunk to N - 2, the same to the in stream count in the server. The crash occurs when the thread waiting for sndbuf is awake and sends the msg in a non-existing stream(N - 1), the call trace is as below: KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f] Call Trace: <TASK> sctp_cmd_send_msg net/sctp/sm_sideeffect.c:1114 [inline] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1777 [inline] sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline] sctp_do_sm+0x197d/0x5310 net/sctp/sm_sideeffect.c:1170 sctp_primitive_SEND+0x9f/0xc0 net/sctp/primitive.c:163 sctp_sendmsg_to_asoc+0x10eb/0x1a30 net/sctp/socket.c:1868 sctp_sendmsg+0x8d4/0x1d90 net/sctp/socket.c:2026 inet_sendmsg+0x9d/0xe0 net/ipv4/af_inet.c:825 sock_sendmsg_nosec net/socket.c:722 [inline] sock_sendmsg+0xde/0x190 net/socket.c:745 The fix is to add an unlikely check for the send stream number after the thread wakes up from the wait_for_sndbuf.

Affected products

• Linux Linux Kernel: from 4.15, before 4.19.281 (fixed in 4.19.281); from 4.20, before 5.4.241 (fixed in 5.4.241); from 5.5, before 5.10.178 (fixed in 5.10.178); from 5.11, before 5.15.107 (fixed in 5.15.107); from 5.16, before 6.1.24 (fixed in 6.1.24); from 6.2, before 6.2.11 (fixed in 6.2.11); …

Published 2025-09-16. Last modified 2026-06-17.