{ "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" } } } }