CVE-2026-64543High· 7.8▾ TwilightIn the Linux kernel, the following vulnerability has been resolved: tipc: fix use-after-free of the discoverer in tipc_disc_rcv() bearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(), but tipc_disc_rcv() still derefer…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 42.9 · likelihood 0 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
Last analysed / modified upstream
0.1%
In the Linux kernel, the following vulnerability has been resolved:
tipc: fix use-after-free of the discoverer in tipc_disc_rcv()
bearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(), but tipc_disc_rcv() still dereferences b->disc in RX softirq under rcu_read_lock() (tipc_udp_recv -> tipc_rcv -> tipc_disc_rcv).
L2 bearers are safe thanks to the synchronize_net() in tipc_disable_l2_media(), but the UDP bearer defers that call to the cleanup_bearer() workqueue, so the discoverer is freed with no grace period:
BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149) Read of size 8 at addr ffff88802348b728 by task poc_tipc/184 <IRQ> tipc_disc_rcv (net/tipc/discover.c:149) tipc_rcv (net/tipc/node.c:2126) tipc_udp_recv (net/tipc/udp_media.c:391) udp_rcv (net/ipv4/udp.c:2643) ip_local_deliver_finish (net/ipv4/ip_input.c:241) </IRQ> Freed by task 181: kfree (mm/slub.c:6565) bearer_disable (net/tipc/bearer.c:418) tipc_nl_bearer_disable (net/tipc/bearer.c:1001)
The bearer is freed with kfree_rcu(); free the discoverer the same way. Add an rcu_head to struct tipc_discoverer and free it and its skb from an RCU callback.
Because the RCU callback (tipc_disc_free_rcu) lives in module text, a call_rcu() that is still pending when the tipc module is unloaded would invoke a freed function. Add an rcu_barrier() to tipc_exit() after the bearer subsystem has been torn down, so all pending discoverer callbacks have run before the module text goes away.
Reachable from an unprivileged user namespace: the TIPCv2 genl family is netnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC and CONFIG_TIPC_MEDIA_UDP.
Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 380413cdfd29fb9fa486c82889132b680c4983c5Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < f05b3f4c78370469286879c765f5a1dd39dbcd32Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 4da2ac7749411971e1b222b992da5a172ce45f98Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 5e215bf1c47fdddf8203a0fe80a0ed594065f101Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < ec7d54d8cc1723921d671e3272b427c96366506fLinux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < b65289e1c3f352a9f92c6e19713ddd647e033253Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 1579342d71133da7f00daa02c75cebec7372097bLinux 4.17Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
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