CVE-2026-74609

CVE CVE-2026-74609EUVD EUVD-2026-64546Published 2026-08-22T15:31:56.000ZLast changed 2026-08-25T05:40:34.000ZCVSS 7.8

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: tipc: read le->link under the node lock in tipc_node_link_down() tipc_node_link_down() caches the link pointer before taking n->lock: struct tipc_link *l = le->link; /* unlocked */ if (!l) return; tipc_node_write_lock(n); if (!tipc_link_is_establishing(l)) { /* deref l */ ... tipc_link_reset(l); /* write into l */ if (delete) { kfree(l); le->link = NULL; The delete=true caller frees that very object under n->lock, so the lock does not protect the cached pointer against it: - CPU A, delete=false: tipc_rcv() on TIPC_LINK_DOWN_EVT, or the link supervision timer via tipc_node_timeout(), reads l unlocked and then dereferences it under n->lock; - CPU B, delete=true: netlink TIPC_NL_BEARER_DISABLE -> bearer_disable() -> tipc_node_delete_links() -> tipc_node_link_down(n, bearer_id, true) -> kfree(l). The link is freed with plain kfree(), not kfree_rcu(), and for UDP bearers disable_media() only schedules the asynchronous cleanup_bearer() work, so its synchronize_net() runs after the links are already gone. An in-flight CPU A that has read l therefore dereferences freed memory once B frees it: a use-after-free read in tipc_link_is_establishing(), and a use-after-free write via tipc_link_reset() on the establishing branch. The following trace was captured on 7.2.0-rc5-00284-gaf39eb111ce6: BUG: KASAN: slab-use-after-free in tipc_link_is_establishing (net/tipc/link.c:285) Read of size 4 at addr ffff88802e2aa068 by task swapper/2/0 tipc_link_is_establishing (net/tipc/link.c:285) tipc_node_link_down (net/tipc/node.c:1076) tipc_node_timeout (net/tipc/node.c:843) Allocated by task 9549: tipc_link_create (net/tipc/link.c:490) tipc_node_check_dest (net/tipc/node.c:1279) tipc_disc_rcv (net/tipc/discover.c:252) tipc_udp_recv (net/tipc/udp_media.c:389) Freed by task 9549: tipc_node_link_down (net/tipc/node.c:1084) tipc_node_delete_links (net/tipc/node.c:1320) bearer_disable (net/tipc/bearer.c:414) __tipc_nl_bearer_disable (net/tipc/bearer.c:992) Move the le->link read inside tipc_node_write_lock(), so it is serialised against the kfree() in the delete path. A racing teardown now either has not run yet, and we see a valid link, or has already run, and we see NULL.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux 73f646cec35477b5099d7e952297cb9e1855be45 <2be741ad565c610871a6a95062c12c39da7168fd; patch: 6.1.183; patch: 6.12.104; patch: 6.18.45; 73f646cec35477b5099d7e952297cb9e1855be45 <c3f2347a47754eac690967cfd82cb6d559817b07; 4.4; 73f646cec35477b5099d7e952297cb9e1855be45 <de017c22135f545ca4e65d1eada22887b64958eb; patch: 0; 73f646cec35477b5099d7e952297cb9e1855be45 <5558a8312452ddb21eff22b1cbd84302ad951944; 73f646cec35477b5099d7e952297cb9e1855be45 <47ba70891b10b2feb52462086b7fcd2ad75d3ce3; patch: 6.6.152; 73f646cec35477b5099d7e952297cb9e1855be45 <a714d62513befef37f71f4ae89bb1fe173b65f2e; patch: 5.15.216; patch: 5.10.265; 73f646cec35477b5099d7e952297cb9e1855be45 <cba9ccb47e9fa4cc77692fb896cc5ab57a667882; patch: 7.1.9; patch: 7.2; 73f646cec35477b5099d7e952297cb9e1855be45 <69d209461c110388710e483a130caf051e4fd09a

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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