{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-38717","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T04:51:24.033Z","datePublished":"2025-09-04T15:33:11.686Z","dateUpdated":"2026-08-05T12:04:14.893Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:04:14.893Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: kcm: Fix race condition in kcm_unattach()\n\nsyzbot found a race condition when kcm_unattach(psock)\nand kcm_release(kcm) are executed at the same time.\n\nkcm_unattach() is missing a check of the flag\nkcm->tx_stopped before calling queue_work().\n\nIf the kcm has a reserved psock, kcm_unattach() might get executed\nbetween cancel_work_sync() and unreserve_psock() in kcm_release(),\nrequeuing kcm->tx_work right before kcm gets freed in kcm_done().\n\nRemove kcm->tx_stopped and replace it by the less\nerror-prone disable_work_sync()."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The race is driven entirely by local syscalls — creating an AF_KCM socket, `SIOCKCMATTACH`/`SIOCKCMUNATTACH` ioctls, and `close()` — with no remote packet needed to reach the vulnerable window. No network-facing service parses attacker data on this path.\nAC:L - The attacker controls both sides of the race, running `kcm_release()` in one thread while a second thread issues `SIOCKCMUNATTACH` on the reserved psock, and can retry the loop indefinitely until the window between `cancel_work_sync()` and `unreserve_psock()` is hit. syzbot hit it repeatedly with three separate reproducers, and `CONFIG_AF_KCM` is shipped as a module by major distributions.\nPR:L - There is not a single `capable()` or `CAP_NET_ADMIN` check in `net/kcm/`, and the protocol family autoloads on an unprivileged `socket(AF_KCM, ...)` call via `MODULE_ALIAS_NETPROTO(PF_KCM)`. Any local unprivileged user can attach a TCP socket and trigger the race.\nUI:N - The attacker performs every step — socket creation, attach, unattach, and close — from its own threads. No victim action or cooperation is required.\nS:U - The use-after-free corrupts kernel heap memory within the same kernel security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The freed `struct kcm_sock` is reachable from a workqueue and is reallocatable by the attacker (its own slab cache, refillable simply by creating more KCM sockets), so the UAF yields a read primitive over adjacent/reused kernel objects and can leak arbitrary kernel memory.\nI:H - Queueing work on a freed object makes the workqueue write into freed memory, and `kcm_tx_work()` subsequently operates on attacker-groomed contents, culminating in the indirect call `sk->sk_write_space(sk)` in `kcm_write_msgs()` — a control-flow hijack / arbitrary-write path, not just corruption.\nA:H - Even unexploited, running `lock_sock()` and `kcm_write_msgs()` on a freed `kcm_sock` produces a KASAN-reported use-after-free, workqueue list corruption, and kernel oops/panic, which any unprivileged user can trigger repeatedly."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/kcm.h","net/kcm/kcmsock.c"],"versions":[{"version":"ab7ac4eb9832e32a09f4e8042705484d2fb0aad3","lessThan":"c0bffbc92a1ca3960fb9cdb8e9f75a68468eb308","status":"affected","versionType":"git"},{"version":"ab7ac4eb9832e32a09f4e8042705484d2fb0aad3","lessThan":"7275dc3bb8f91b23125ff3f47b6529935cf46152","status":"affected","versionType":"git"},{"version":"ab7ac4eb9832e32a09f4e8042705484d2fb0aad3","lessThan":"798733ee5d5788b12e8a52db1519abc17e826f69","status":"affected","versionType":"git"},{"version":"ab7ac4eb9832e32a09f4e8042705484d2fb0aad3","lessThan":"52565a935213cd6a8662ddb8efe5b4219343a25d","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/kcm.h","net/kcm/kcmsock.c"],"versions":[{"version":"4.6","status":"affected"},{"version":"0","lessThan":"4.6","status":"unaffected","versionType":"semver"},{"version":"6.12.43","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.15.11","lessThanOrEqual":"6.15.*","status":"unaffected","versionType":"semver"},{"version":"6.16.2","lessThanOrEqual":"6.16.*","status":"unaffected","versionType":"semver"},{"version":"6.17","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.6","versionEndExcluding":"6.12.43"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.6","versionEndExcluding":"6.15.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.6","versionEndExcluding":"6.16.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.6","versionEndExcluding":"6.17"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/c0bffbc92a1ca3960fb9cdb8e9f75a68468eb308"},{"url":"https://git.kernel.org/stable/c/7275dc3bb8f91b23125ff3f47b6529935cf46152"},{"url":"https://git.kernel.org/stable/c/798733ee5d5788b12e8a52db1519abc17e826f69"},{"url":"https://git.kernel.org/stable/c/52565a935213cd6a8662ddb8efe5b4219343a25d"}],"title":"net: kcm: Fix race condition in kcm_unattach()","x_generator":{"engine":"bippy-1.2.0"}}}}