{"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":"2026-08-25T05:40:34.778Z"},"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"}}}}