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CVE-2026-52928: af_unix: Reject SIOCATMARK on non-stream sockets

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-24 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: af_unix: Reject SIOCATMARK on non-stream sockets SIOCATMARK reports whether the receive queue is at the urgent mark for MSG_OOB. In AF_UNIX, MSG_OOB is supported only for SOCK_STREAM sockets. SOCK_DGRAM and SOCK_SEQPACKET reject MSG_OOB in sendmsg() and recvmsg(), so they should not support SIOCATMARK either. Return -EOPNOTSUPP for non-stream sockets before checking the receive queue.

Affected products

• Linux kernel: from 5.15 before 5.15.211; from 5.16 before 6.1.177; from 6.2 before 6.6.144; from 6.7 before 6.12.88; from 6.13 before 6.18.30; from 6.19 before 7.0.7 — fixed in 5.15.211, 6.1.177, 6.12.88, 6.18.30, 6.6.144, 7.0.7

How to fix

Upgrade to a fixed version: Linux kernel 5.15.211, 6.1.177, 6.12.88, 6.18.30. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/3147ddf5a41c20c45c2eb69e00b62f10f822056a
• https://git.kernel.org/stable/c/645b1ed3259af38b7814242a420bc2081bdd1eb6
• https://git.kernel.org/stable/c/b741c9c6ef59f17c1f104ddf1217ef77f79ed29b
• https://git.kernel.org/stable/c/c34c41446acf6c0d13b5b06c809be11e0f7f2729
• https://git.kernel.org/stable/c/d119775f2bad827edc28071c061fdd4a91f889a5
• https://git.kernel.org/stable/c/ec123873fdc83e7244c8ed6d17b8f8ea6c416a67
• https://git.kernel.org/stable/c/f085971de6d6b8ef946a5e0bcd73ff24509a0f85
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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