Linux Kernel Vulnerability in AF_UNIX Networking Support

CVE-2026-52928

What is CVE-2026-52928?

A vulnerability within the Linux kernel's AF_UNIX networking implementation allows for improper handling of SIOCATMARK on non-stream sockets. This issue arises because SIOCATMARK is designed to ascertain if the receive queue is at an urgent mark for the MSG_OOB option, which is only applicable to SOCK_STREAM sockets. Currently, SOCK_DGRAM and SOCK_SEQPACKET reject MSG_OOB in their sendmsg() and recvmsg() functions, creating a scenario where SIOCATMARK should not be supported for these socket types. The resolution necessitates returning -EOPNOTSUPP for non-stream sockets prior to checking the receive queue, thereby improving the kernel’s reliability and security.

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