{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74628", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.921Z", "datePublished": "2026-08-22T15:32:10.135Z", "dateUpdated": "2026-08-27T12:39:49.703Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-27T12:39:49.703Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/x25: fix use-after-free of the socket by its timers\n\nThe x25 timers are armed with mod_timer() and cancelled with\ntimer_delete(), so a pending timer holds no reference on the socket and a\ncancel does not wait for a callback already running on another CPU.\n\nx25_heartbeat_expiry() also rearms unconditionally, so it can reinstall\nsk->sk_timer after __x25_destroy_socket() has passed its cancel point.\nThe following __sock_put() frees the socket while the timer is still\nqueued, and the next expiry uses freed memory. KASAN reports a\nslab-use-after-free on the kmalloc-2k object freed by close().\n\ntimer_delete_sync() cannot be used here: x25_heartbeat_expiry() and\nx25_timer_expiry() both reach the cancels from inside the timer they\nwould wait on, through __x25_destroy_socket() and x25_disconnect().\n\nArm the timers with sk_reset_timer() and cancel them with sk_stop_timer()\nso that an armed timer owns a reference, and release it in both expiry\nhandlers. Rearm the heartbeat only while sk_hashed(sk) is still true,\nsince __x25_destroy_socket() unlinks the socket before dropping it. Arm\nthe deferred destroy timer the same way and drop its reference in\nx25_destroy_timer().\n\nReproduced on net with KASAN, with the heartbeat period shortened so the\nwindow recurs. With this patch the reproducer no longer triggers a\nreport and /proc/net/x25 drains.\n\nDiscovered by XBOW, triaged by Baul Lee " } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - Remote X.25 frames reach x25_lapb_receive_frame() on init_net gateways, where unauthenticated CALL_REQUEST/CLEAR handling arms heartbeat timers and drives server socket teardown through __x25_destroy_socket() during close.\nAC:L - The attacker controls both sides of the race by opening/closing sockets or sending concurrent connect/clear traffic, repeatedly forcing __x25_destroy_socket() against sk_timer callbacks that re-arm via mod_timer().\nPR:N - X.25 call setup and clearing are unauthenticated on the wire; a remote peer can create sockets via CALL_REQUEST and force teardown without any local account or CAP_NET_ADMIN.\nUI:N - Exploitation requires no end-user action; automated server handling of remote X.25 connect/clear suffices to reach the vulnerable close/timer path.\nS:U - Impact stays within kernel memory via standard slab UAF on the AF_X25 socket object; this is not a guest/host or IOMMU boundary escape.\nC:H - KASAN reports slab-use-after-free on the kmalloc-2k socket freed by close(), and UAF on struct sock gives attacker-controlled reuse enabling arbitrary kernel memory disclosure.\nI:H - Use-after-free of the socket structure enables heap grooming and corrupting freed object contents for control-flow or arbitrary kernel writes/code execution.\nA:H - The freed socket timer expiry dereferences released memory and can oops/panic the kernel; UAF reliably threatens system availability even before full exploitation." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/x25/af_x25.c", "net/x25/x25_timer.c" ], "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "ba925a2e98ce967a0e71c5bcbcf5dbd3facaf0c8", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "6b79659590f0f82a9b8efd2ffd55ec6399ebfc33", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "fdd9ac50b9b61ef2b2d52c5156aff788be91454d", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "3c4919be5d910db4beebca420953858606fba7d8", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "4bc522b33438fefc3272840ae5988771863a4f1f", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "e92c7e2b41d1528a830bc64c5e4e46dfa8133dda", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "2195424c3da2ef1829a63b807e3a900a90e57d85", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/x25/af_x25.c", "net/x25/x25_timer.c" ], "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.267", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.217", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.184", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.153", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.105", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.45", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.9", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "2.6.12", "versionEndExcluding": "5.10.267" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.15.217" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.1.184" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.6.153" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.12.105" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.18.45" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.1.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/ba925a2e98ce967a0e71c5bcbcf5dbd3facaf0c8" }, { "url": "https://git.kernel.org/stable/c/6b79659590f0f82a9b8efd2ffd55ec6399ebfc33" }, { "url": "https://git.kernel.org/stable/c/fdd9ac50b9b61ef2b2d52c5156aff788be91454d" }, { "url": "https://git.kernel.org/stable/c/1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6" }, { "url": "https://git.kernel.org/stable/c/3c4919be5d910db4beebca420953858606fba7d8" }, { "url": "https://git.kernel.org/stable/c/4bc522b33438fefc3272840ae5988771863a4f1f" }, { "url": "https://git.kernel.org/stable/c/e92c7e2b41d1528a830bc64c5e4e46dfa8133dda" }, { "url": "https://git.kernel.org/stable/c/2195424c3da2ef1829a63b807e3a900a90e57d85" } ], "title": "net/x25: fix use-after-free of the socket by its timers", "x_generator": { "engine": "bippy-1.2.0" } } } }