cbcvebase.
CVE-2026-23394
published 2026-03-25

CVE-2026-23394: In the Linux kernel, the following vulnerability has been resolved: af_unix: Give up GC if MSG_PEEK intervened. Igor Ushakov reported that GC purged the…

PriorityP418medium4.7CVSS 3.1
AVLACHPRLUINSUCNINAH
EPSS
0.09%
0.5th percentile
In the Linux kernel, the following vulnerability has been resolved: af_unix: Give up GC if MSG_PEEK intervened. Igor Ushakov reported that GC purged the receive queue of an alive socket due to a race with MSG_PEEK with a nice repro. This is the exact same issue previously fixed by commit cbcf01128d0a ("af_unix: fix garbage collect vs MSG_PEEK"). After GC was replaced with the current algorithm, the cited commit removed the locking dance in unix_peek_fds() and reintroduced the same issue. The problem is that MSG_PEEK bumps a file refcount without interacting with GC. Consider an SCC containing sk-A and sk-B, where sk-A is close()d but can be recv()ed via sk-B. The bad thing happens if sk-A is recv()ed with MSG_PEEK from sk-B and sk-B is close()d while GC is checking unix_vertex_dead() for sk-A and sk-B. GC thread User thread --------- ----------- unix_vertex_dead(sk-A) -> true sk-A's file refcount : 1 -> 2 close(sk-B) -> sk-B's file refcount : 2 -> 1 unix_vertex_dead(sk-B) -> true Initially, sk-A's file refcount is 1 by the inflight fd in sk-B recvq. GC thinks sk-A is dead because the file refcount is the same as the number of its inflight fds. However, sk-A's file refcount is bumped silently by MSG_PEEK, which invalidates the previous evaluation. At this moment, sk-B's file refcount is 2; one by the open fd, and one by the inflight fd in sk-A. The subsequent close() releases one refcount by the former. Finally, GC incorrectly concludes that both sk-A and sk-B are dead. One option is to restore the locking dance in unix_peek_fds(), but we can resolve this more elegantly thanks to the new algorithm. The point is that the issue does not occur without the subsequent close() and we actually do not need to synchronise MSG_PEEK with the dead SCC detection. When the issue occurs, close() and GC touch the same file refcount. If GC sees the refcount being decremented by close(), it can just give up garbage-collecting the SCC. Therefore, we only need to signal

Affected

51 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.19.10-1 (forky)linux 6.19.10-1 (forky)
linuxlinux
linuxlinux
linuxlinux>= 118f457da9ed58a79e24b73c2ef0aa1987241f0e < e3dd56fb5683ba80bf8d7a2f9aa21cfa53f05202e3dd56fb5683ba80bf8d7a2f9aa21cfa53f05202
linuxlinux>= 118f457da9ed58a79e24b73c2ef0aa1987241f0e < 72cf49ad50c16270b52bc512d9c2df574392296872cf49ad50c16270b52bc512d9c2df5743922968
linuxlinux>= 118f457da9ed58a79e24b73c2ef0aa1987241f0e < 37dd7ab332396eb8dd80b2dc7ea4b61abf76743637dd7ab332396eb8dd80b2dc7ea4b61abf767436
linuxlinux>= 118f457da9ed58a79e24b73c2ef0aa1987241f0e < e5b31d988a41549037b8d8721a3c3cae893d8670e5b31d988a41549037b8d8721a3c3cae893d8670
linuxlinux>= 6.1.141 < 6.26.2
linuxlinux>= 6.6.93 < 6.6.1426.6.142
linuxlinux>= 7b1ffbd3b22e755d481d49647dcb7c5cfbde5844 < 3106f326f67c03dd9da4ca64663d11e40138cf403106f326f67c03dd9da4ca64663d11e40138cf40
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.19.10-16.19.10-1
linuxlinux_kernel>= 6.1.141 < 6.26.2
linuxlinux_kernel>= 6.10.0 < 6.19.106.19.10
linuxlinux_kernel>= 6.10.1 < 6.18.236.18.23
linuxlinux_kernel>= 6.19 < 6.19.106.19.10
linuxlinux_kernel>= 6.6.93 < 6.76.7
ubuntulinux
ubuntulinux-aws
ubuntulinux-aws-6.17
ubuntulinux-aws-fips
ubuntulinux-azure
ubuntulinux-azure-6.17
ubuntulinux-azure-6.8

CVSS provenance

nvdv3.14.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
vendor_ubuntu7.8HIGH
vendor_redhat5.5MEDIUM
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