{"id":"CVE-2026-64543","title":"tipc: fix use-after-free of the discoverer in tipc_disc_rcv()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix use-after-free of the discoverer in tipc_disc_rcv()\n\nbearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(),\nbut tipc_disc_rcv() still derefer…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 380413cdfd29fb9fa486c82889132b680c4983c5","Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < f05b3f4c78370469286879c765f5a1dd39dbcd32","Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 4da2ac7749411971e1b222b992da5a172ce45f98","Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 5e215bf1c47fdddf8203a0fe80a0ed594065f101","Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < ec7d54d8cc1723921d671e3272b427c96366506f","Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2","Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < b65289e1c3f352a9f92c6e19713ddd647e033253","Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 1579342d71133da7f00daa02c75cebec7372097b","Linux 4.17"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:42:12.338756Z"},"published":"2026-07-27","updated":"2026-10-16","sourceUpdated":"2026-10-16T15:52:51.300Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64543","references":[{"url":"https://git.kernel.org/stable/c/380413cdfd29fb9fa486c82889132b680c4983c5"},{"url":"https://git.kernel.org/stable/c/f05b3f4c78370469286879c765f5a1dd39dbcd32"},{"url":"https://git.kernel.org/stable/c/4da2ac7749411971e1b222b992da5a172ce45f98"},{"url":"https://git.kernel.org/stable/c/5e215bf1c47fdddf8203a0fe80a0ed594065f101"},{"url":"https://git.kernel.org/stable/c/ec7d54d8cc1723921d671e3272b427c96366506f"},{"url":"https://git.kernel.org/stable/c/a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2"},{"url":"https://git.kernel.org/stable/c/b65289e1c3f352a9f92c6e19713ddd647e033253"},{"url":"https://git.kernel.org/stable/c/1579342d71133da7f00daa02c75cebec7372097b"}],"tags":["cve.org"],"epss":0.00126,"epssPercentile":0.02035,"ingestedAt":"2026-10-16T17:24:46.833Z","slug":"CVE-2026-64543","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix use-after-free of the discoverer in tipc_disc_rcv()\n\nbearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(),\nbut tipc_disc_rcv() still dereferences b->disc in RX softirq under\nrcu_read_lock() (tipc_udp_recv -> tipc_rcv -> tipc_disc_rcv).\n\nL2 bearers are safe thanks to the synchronize_net() in\ntipc_disable_l2_media(), but the UDP bearer defers that call to the\ncleanup_bearer() workqueue, so the discoverer is freed with no grace\nperiod:\n\n BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149)\n Read of size 8 at addr ffff88802348b728 by task poc_tipc/184\n <IRQ>\n  tipc_disc_rcv (net/tipc/discover.c:149)\n  tipc_rcv (net/tipc/node.c:2126)\n  tipc_udp_recv (net/tipc/udp_media.c:391)\n  udp_rcv (net/ipv4/udp.c:2643)\n  ip_local_deliver_finish (net/ipv4/ip_input.c:241)\n </IRQ>\n Freed by task 181:\n  kfree (mm/slub.c:6565)\n  bearer_disable (net/tipc/bearer.c:418)\n  tipc_nl_bearer_disable (net/tipc/bearer.c:1001)\n\nThe bearer is freed with kfree_rcu(); free the discoverer the same way.\nAdd an rcu_head to struct tipc_discoverer and free it and its skb from an\nRCU callback.\n\nBecause the RCU callback (tipc_disc_free_rcu) lives in module text, a\ncall_rcu() that is still pending when the tipc module is unloaded would\ninvoke a freed function. Add an rcu_barrier() to tipc_exit() after the\nbearer subsystem has been torn down, so all pending discoverer callbacks\nhave run before the module text goes away.\n\nReachable from an unprivileged user namespace: the TIPCv2 genl family is\nnetnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC\nand CONFIG_TIPC_MEDIA_UDP.\n\n## Affected\n\n- `Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 380413cdfd29fb9fa486c82889132b680c4983c5`\n- `Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < f05b3f4c78370469286879c765f5a1dd39dbcd32`\n- `Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 4da2ac7749411971e1b222b992da5a172ce45f98`\n- `Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 5e215bf1c47fdddf8203a0fe80a0ed594065f101`\n- `Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < ec7d54d8cc1723921d671e3272b427c96366506f`\n- `Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2`\n- `Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < b65289e1c3f352a9f92c6e19713ddd647e033253`\n- `Linux >= 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 < 1579342d71133da7f00daa02c75cebec7372097b`\n- `Linux 4.17`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}