CVE Catalog

CVE-2026-97985

Unknown
Published: Translated: NVD NIST

Summary

In the Linux kernel, the AF_UNIX subsystem has a bug in manage_oob() that fails to update the last skb marker. As a result, a blocking recv(MSG_PEEK) call can hog CPU by busy-waiting for a new skb. The fix updates the @last marker in manage_oob().

Risk Assessment

Excessive CPU consumption (busy-wait) by applications using AF_UNIX sockets with MSG_PEEK can lead to denial of service. This affects systems with local inter-process communication.

Recommendation

Update the Linux kernel to a version with the fix. Monitor CPU usage by applications using AF_UNIX sockets.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: af_unix: Update last skb marker in manage_oob(). Fahad Alharbi reported that blocking recv(MSG_PEEK) could hog CPU due to OOB skb. In the following cases, manage_oob() skips OOB skb(s) and returns NULL for the last recv(MSG_PEEK): socketpair(AF_UNIX, SOCK_STREAM, 0, sk); 1) skb -> OOB skb -> NULL send(sk[0], "ab", 2, MSG_OOB); recv(sk[1], buf, 0, MSG_PEEK); 2) skb -> consumed OOB skb -> NULL send(sk[0], "ab", 2, MSG_OOB); recv(sk[1], buf, 1, MSG_OOB); recv(sk[1], buf, 0, MSG_PEEK); 3) consumed OOB skb -> OOB skb -> NULL send(sk[0], "a", 1, MSG_OOB); recv(sk[1], buf, 0, MSG_OOB); send(sk[0], "b", 1, MSG_OOB); recv(sk[1], buf, 1, MSG_PEEK); Then, @copied is 0 in unix_stream_read_generic() (zero-length buffer, or non-OOB skb is not yet consumed), and unix_stream_data_wait() is called. However, it returns immediately because @last is not updated in unix_stream_read_generic(), and the thread busy-waits for a new skb. Let's update @last in manage_oob(). For MSG_PEEK, @last is updated with the skipped OOB, and for the non-peek case, @last matches the returned value (when !copied) because OOB is unlinked. Note that manage_oob() is inlined and no stack canary is added.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS