{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74609", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.920Z", "datePublished": "2026-08-22T15:31:56.054Z", "dateUpdated": "2026-10-16T19:06:01.059Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-25T05:40:34.778Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: read le->link under the node lock in tipc_node_link_down()\n\ntipc_node_link_down() caches the link pointer before taking n->lock:\n\n\tstruct tipc_link *l = le->link;\t\t/* unlocked */\n\n\tif (!l)\n\t\treturn;\n\ttipc_node_write_lock(n);\n\tif (!tipc_link_is_establishing(l)) {\t/* deref l */\n\t...\n\t\ttipc_link_reset(l);\t\t/* write into l */\n\tif (delete) {\n\t\tkfree(l);\n\t\tle->link = NULL;\n\nThe delete=true caller frees that very object under n->lock, so the lock\ndoes not protect the cached pointer against it:\n\n - CPU A, delete=false: tipc_rcv() on TIPC_LINK_DOWN_EVT, or the link\n supervision timer via tipc_node_timeout(), reads l unlocked and then\n dereferences it under n->lock;\n - CPU B, delete=true: netlink TIPC_NL_BEARER_DISABLE -> bearer_disable()\n -> tipc_node_delete_links() -> tipc_node_link_down(n, bearer_id, true)\n -> kfree(l).\n\nThe link is freed with plain kfree(), not kfree_rcu(), and for UDP bearers\ndisable_media() only schedules the asynchronous cleanup_bearer() work, so\nits synchronize_net() runs after the links are already gone. An in-flight\nCPU A that has read l therefore dereferences freed memory once B frees it:\na use-after-free read in tipc_link_is_establishing(), and a use-after-free\nwrite via tipc_link_reset() on the establishing branch.\n\nThe following trace was captured on 7.2.0-rc5-00284-gaf39eb111ce6:\n\n BUG: KASAN: slab-use-after-free in tipc_link_is_establishing (net/tipc/link.c:285)\n Read of size 4 at addr ffff88802e2aa068 by task swapper/2/0\n tipc_link_is_establishing (net/tipc/link.c:285)\n tipc_node_link_down (net/tipc/node.c:1076)\n tipc_node_timeout (net/tipc/node.c:843)\n Allocated by task 9549:\n tipc_link_create (net/tipc/link.c:490)\n tipc_node_check_dest (net/tipc/node.c:1279)\n tipc_disc_rcv (net/tipc/discover.c:252)\n tipc_udp_recv (net/tipc/udp_media.c:389)\n Freed by task 9549:\n tipc_node_link_down (net/tipc/node.c:1084)\n tipc_node_delete_links (net/tipc/node.c:1320)\n bearer_disable (net/tipc/bearer.c:414)\n __tipc_nl_bearer_disable (net/tipc/bearer.c:992)\n\nMove the le->link read inside tipc_node_write_lock(), so it is serialised\nagainst the kfree() in the delete path. A racing teardown now either has\nnot run yet, and we see a valid link, or has already run, and we see NULL." } ], "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 UAF race requires the delete=true path (kfree) via TIPC_NL_BEARER_DISABLE/bearer_disable() or netns teardown, reachable only through local RTNL/genlink with CAP_NET_ADMIN; remote tipc_rcv() packets alone cannot free links and complete the race.\nAC:L - An attacker with CAP_NET_ADMIN controls both CPUs by scripting bearer disable/netns teardown while concurrently driving link-down events via TIPC traffic or link supervision timers; KASAN reproduced this reliably without uncontrollable victim timing.\nPR:L - Bearer disable and link deletion require CAP_NET_ADMIN (GENL_UNS_ADMIN_PERM on TIPC_NL_BEARER_DISABLE); tipc_genl_family is netns-aware, so unprivileged users obtain effective net-admin via user/network namespaces (unshare -Urn).\nUI:N - No victim interaction is required; the attacker scripts bearer teardown and concurrent TIPC link activity from their own processes without needing another user to mount, open files, or perform administrative actions.\nS:U - Slab UAF corrupts host kernel heap memory within the same kernel security authority; impact is kernel crash or local privilege escalation, not a VM, IOMMU, or cross-container sandbox boundary escape.\nC:H - Slab use-after-free read in tipc_link_is_establishing() dereferences freed tipc_link objects (KASAN-confirmed), enabling disclosure of freed kernel memory and supporting further heap exploitation primitives.\nI:H - On the establishing branch tipc_link_reset() performs multiple writes into the freed tipc_link structure, corrupting kernel heap metadata and adjacent objects in ways exploitable for arbitrary write and control-flow hijacking.\nA:H - KASAN-confirmed slab-use-after-free in tipc_node_link_down() causes kernel oops/panic (observed on swapper during tipc_node_timeout), and the race can be retriggered during bearer teardown loops for reliable denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/tipc/node.c" ], "versions": [ { "version": "73f646cec35477b5099d7e952297cb9e1855be45", "lessThan": "2be741ad565c610871a6a95062c12c39da7168fd", "status": "affected", "versionType": "git" }, { "version": "73f646cec35477b5099d7e952297cb9e1855be45", "lessThan": "69d209461c110388710e483a130caf051e4fd09a", "status": "affected", "versionType": "git" }, { "version": "73f646cec35477b5099d7e952297cb9e1855be45", "lessThan": "de017c22135f545ca4e65d1eada22887b64958eb", "status": "affected", "versionType": "git" }, { "version": "73f646cec35477b5099d7e952297cb9e1855be45", "lessThan": "47ba70891b10b2feb52462086b7fcd2ad75d3ce3", "status": "affected", "versionType": "git" }, { "version": "73f646cec35477b5099d7e952297cb9e1855be45", "lessThan": "a714d62513befef37f71f4ae89bb1fe173b65f2e", "status": "affected", "versionType": "git" }, { "version": "73f646cec35477b5099d7e952297cb9e1855be45", "lessThan": "c3f2347a47754eac690967cfd82cb6d559817b07", "status": "affected", "versionType": "git" }, { "version": "73f646cec35477b5099d7e952297cb9e1855be45", "lessThan": "5558a8312452ddb21eff22b1cbd84302ad951944", "status": "affected", "versionType": "git" }, { "version": "73f646cec35477b5099d7e952297cb9e1855be45", "lessThan": "cba9ccb47e9fa4cc77692fb896cc5ab57a667882", "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/tipc/node.c" ], "versions": [ { "version": "4.4", "status": "affected" }, { "version": "0", "lessThan": "4.4", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.265", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.152", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.104", "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": "4.4", "versionEndExcluding": "5.10.265" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "5.15.216" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.1.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.6.152" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.12.104" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.18.45" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "7.1.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/2be741ad565c610871a6a95062c12c39da7168fd" }, { "url": "https://git.kernel.org/stable/c/69d209461c110388710e483a130caf051e4fd09a" }, { "url": "https://git.kernel.org/stable/c/de017c22135f545ca4e65d1eada22887b64958eb" }, { "url": "https://git.kernel.org/stable/c/47ba70891b10b2feb52462086b7fcd2ad75d3ce3" }, { "url": "https://git.kernel.org/stable/c/a714d62513befef37f71f4ae89bb1fe173b65f2e" }, { "url": "https://git.kernel.org/stable/c/c3f2347a47754eac690967cfd82cb6d559817b07" }, { "url": "https://git.kernel.org/stable/c/5558a8312452ddb21eff22b1cbd84302ad951944" }, { "url": "https://git.kernel.org/stable/c/cba9ccb47e9fa4cc77692fb896cc5ab57a667882" } ], "title": "tipc: read le->link under the node lock in tipc_node_link_down()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-74609", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:02:14.527164Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:06:01.059Z" } } ] } }