{"cve":"CVE-2026-74609","nvd":{"published":"2026-08-22T16:16:33.407","modified":"2026-10-16T20:17:46.070","status":"Received","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/2be741ad565c610871a6a95062c12c39da7168fd","https://git.kernel.org/stable/c/47ba70891b10b2feb52462086b7fcd2ad75d3ce3","https://git.kernel.org/stable/c/5558a8312452ddb21eff22b1cbd84302ad951944","https://git.kernel.org/stable/c/69d209461c110388710e483a130caf051e4fd09a","https://git.kernel.org/stable/c/a714d62513befef37f71f4ae89bb1fe173b65f2e"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:49:38.260478770+00:00"},"epss":{"cve":"CVE-2026-74609","score":0.00126,"percentile":0.02234,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}