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CVE-2026-23394— af_unix: Give up GC if MSG_PEEK intervened.

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于垃圾回收与MSG_PEEK操作竞争，可能导致过早释放。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.09% · P1

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 61a75360dca93c945ef6bd757f8b8a96f39b77cb< 980999a96e1ad043f1197606e5d637219cb102b9 affected
7b1ffbd3b22e755d481d49647dcb7c5cfbde5844< 3106f326f67c03dd9da4ca64663d11e40138cf40 affected
118f457da9ed58a79e24b73c2ef0aa1987241f0e< e3dd56fb5683ba80bf8d7a2f9aa21cfa53f05202 affected
118f457da9ed58a79e24b73c2ef0aa1987241f0e< 72cf49ad50c16270b52bc512d9c2df5743922968 affected
118f457da9ed58a79e24b73c2ef0aa1987241f0e< 37dd7ab332396eb8dd80b2dc7ea4b61abf767436 affected
118f457da9ed58a79e24b73c2ef0aa1987241f0e< e5b31d988a41549037b8d8721a3c3cae893d8670 affected
6.1.141< 6.1.183 affected
6.6.93< 6.6.142 affected
… +8 more rows
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I. Basic Information for CVE-2026-23394

Vulnerability Information
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Vulnerability Title
af_unix: Give up GC if MSG_PEEK intervened.
Source: CVE Program / CVE List V5
Vulnerability Description
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 <------. \ `------ recv(sk-B, MSG_PEEK) invalidate !! -> 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 the race during MSG_PEEK with a proper memory barrier to make it visible to the GC. Let's use seqcount_t to notify GC when MSG_PEEK occurs and let it defer the SCC to the next run. This way no locking is needed on the MSG_PEEK side, and we can avoid imposing a penalty on every MSG_PEEK unnecessarily. Note that we can retry within unix_scc_dead() if MSG_PEEK is detected, but we do not do so to avoid hung task splat from abusive MSG_PEEK calls.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于垃圾回收与MSG_PEEK操作竞争，可能导致过早释放。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 61a75360dca93c945ef6bd757f8b8a96f39b77cb ~ 980999a96e1ad043f1197606e5d637219cb102b9 -
Linux Linux 6.10 -

II. Public POCs for CVE-2026-23394

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III. Intelligence Information for CVE-2026-23394

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Patches & Fixes for CVE-2026-23394 (4)

Same Patch Batch · Linux · 2026-03-25 · 116 CVEs total

CVE-2026-23395 8.8 HIGH Bluetooth: L2CAP: Fix accepting multiple L2CAP_ECRED_CONN_REQ
CVE-2026-31788 8.2 HIGH xen/privcmd: restrict usage in unprivileged domU
CVE-2026-23340 7.8 HIGH net: sched: avoid qdisc_reset_all_tx_gt() vs dequeue race for lockless qdiscs
CVE-2026-23336 7.8 HIGH wifi: cfg80211: cancel rfkill_block work in wiphy_unregister()
CVE-2026-23350 7.8 HIGH drm/xe/queue: Call fini on exec queue creation fail
CVE-2026-23351 7.8 HIGH netfilter: nft_set_pipapo: split gc into unlink and reclaim phase
CVE-2026-23317 7.8 HIGH drm/vmwgfx: Return the correct value in vmw_translate_ptr functions
CVE-2026-23306 7.8 HIGH scsi: pm8001: Fix use-after-free in pm8001_queue_command()
CVE-2026-23372 7.8 HIGH nfc: rawsock: cancel tx_work before socket teardown
CVE-2026-23378 7.8 HIGH net/sched: act_ife: Fix metalist update behavior
CVE-2026-23383 7.8 HIGH bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
CVE-2026-23393 7.8 HIGH bridge: cfm: Fix race condition in peer_mep deletion
CVE-2026-23391 7.8 HIGH netfilter: xt_CT: drop pending enqueued packets on template removal
CVE-2026-23288 7.8 HIGH accel/amdxdna: Fix out-of-bounds memset in command slot handling
CVE-2026-23280 7.8 HIGH accel/amdxdna: Prevent ubuf size overflow
CVE-2026-23392 7.8 HIGH netfilter: nf_tables: release flowtable after rcu grace period on error
CVE-2026-23364 7.4 HIGH ksmbd: Compare MACs in constant time
CVE-2026-23294 7.0 HIGH bpf: Fix race in devmap on PREEMPT_RT
CVE-2026-23356 drbd: fix "LOGIC BUG" in drbd_al_begin_io_nonblock()
CVE-2026-23352 x86/efi: defer freeing of boot services memory

Showing top 20 of 116 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23394

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