{"id":"CVE-2026-74255","state":"PUBLISHED","title":"tipc: fix UAF in tipc_l2_send_msg()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix UAF in tipc_l2_send_msg()\n\nSyzbot reported a slab-use-after-free in ipvlan_hard_header() when\ncalled from tipc_l2_send_msg().\n\nThe root cause is that tipc_disable_l2_media() calls synchronize_net()\nwhile b->media_ptr is still valid. This allows concurrent RCU readers\nto obtain the device pointer after synchronize_net() has finished.\nThe pointer is cleared later in bearer_disable(), but without any\nsubsequent synchronization, allowing the device to be freed while\nstill in use by readers.\n\nFix this by clearing b->media_ptr in tipc_disable_l2_media() before\ncalling synchronize_net().\n\nThis is safe to do now because the call order in bearer_disable()\nwas reversed in 0d051bf93c06 (\"tipc: make bearer packet filtering generic\")\nto call tipc_node_delete_links() (which needs the pointer) before\ndisable_media().\n\nhttps: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u","publishedAt":"2026-08-15T05:57:34.293Z","updatedAt":"2026-10-16T18:55:27.929Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"609ced2301be1df7e7ed2ef47d1d916674e6ba3b","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"71aafa16d79b107b33837f60b6cbc7d0cb8c5708","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"f4002f1c669cc02e3763f479fc25ff1dfa9e2420","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"50ff092633b06382e5091dd5b093ce943d4ac2f9","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"aef12b5ce793dea6b3a97a58fd0f946000ae8945","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"0d8a12d7143126afdf9fbe2e3d438650dd6603ed","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"35e0297a93c3c34a3924eeef816c03504e3ab5c5","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tipc/bearer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.4","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tipc/bearer.c"]}],"references":["https://git.kernel.org/stable/c/609ced2301be1df7e7ed2ef47d1d916674e6ba3b","https://git.kernel.org/stable/c/71aafa16d79b107b33837f60b6cbc7d0cb8c5708","https://git.kernel.org/stable/c/f4002f1c669cc02e3763f479fc25ff1dfa9e2420","https://git.kernel.org/stable/c/50ff092633b06382e5091dd5b093ce943d4ac2f9","https://git.kernel.org/stable/c/aef12b5ce793dea6b3a97a58fd0f946000ae8945","https://git.kernel.org/stable/c/0d8a12d7143126afdf9fbe2e3d438650dd6603ed","https://git.kernel.org/stable/c/35e0297a93c3c34a3924eeef816c03504e3ab5c5","https://git.kernel.org/stable/c/f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74255.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74255","state":"PUBLISHED","datePublished":"2026-08-15T05:57:34.293Z","dateUpdated":"2026-10-16T18:55:27.929Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.876Z"},"containers":{"cna":{"title":"tipc: fix UAF in tipc_l2_send_msg()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix UAF in tipc_l2_send_msg()\n\nSyzbot reported a slab-use-after-free in ipvlan_hard_header() when\ncalled from tipc_l2_send_msg().\n\nThe root cause is that tipc_disable_l2_media() calls synchronize_net()\nwhile b->media_ptr is still valid. This allows concurrent RCU readers\nto obtain the device pointer after synchronize_net() has finished.\nThe pointer is cleared later in bearer_disable(), but without any\nsubsequent synchronization, allowing the device to be freed while\nstill in use by readers.\n\nFix this by clearing b->media_ptr in tipc_disable_l2_media() before\ncalling synchronize_net().\n\nThis is safe to do now because the call order in bearer_disable()\nwas reversed in 0d051bf93c06 (\"tipc: make bearer packet filtering generic\")\nto call tipc_node_delete_links() (which needs the pointer) before\ndisable_media().\n\nhttps: //lore.kernel.org/netdev/6a2c1007.428ffe26.258b27.015d.GAE@google.com/T/#u"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"609ced2301be1df7e7ed2ef47d1d916674e6ba3b","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"71aafa16d79b107b33837f60b6cbc7d0cb8c5708","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"f4002f1c669cc02e3763f479fc25ff1dfa9e2420","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"50ff092633b06382e5091dd5b093ce943d4ac2f9","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"aef12b5ce793dea6b3a97a58fd0f946000ae8945","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"0d8a12d7143126afdf9fbe2e3d438650dd6603ed","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"35e0297a93c3c34a3924eeef816c03504e3ab5c5","versionType":"git"},{"version":"282b3a056225b35024246f63feb91d769d714dad","status":"affected","lessThan":"f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tipc/bearer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.4","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tipc/bearer.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/609ced2301be1df7e7ed2ef47d1d916674e6ba3b"},{"url":"https://git.kernel.org/stable/c/71aafa16d79b107b33837f60b6cbc7d0cb8c5708"},{"url":"https://git.kernel.org/stable/c/f4002f1c669cc02e3763f479fc25ff1dfa9e2420"},{"url":"https://git.kernel.org/stable/c/50ff092633b06382e5091dd5b093ce943d4ac2f9"},{"url":"https://git.kernel.org/stable/c/aef12b5ce793dea6b3a97a58fd0f946000ae8945"},{"url":"https://git.kernel.org/stable/c/0d8a12d7143126afdf9fbe2e3d438650dd6603ed"},{"url":"https://git.kernel.org/stable/c/35e0297a93c3c34a3924eeef816c03504e3ab5c5"},{"url":"https://git.kernel.org/stable/c/f4c3d89fc986b0da196ddfc6cfe0ea5d5d08bec6"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - tipc_l2_send_msg is reached from tipc_bearer_xmit during L2 TIPC protocol handling; remote ETH_P_TIPC frames on cluster/datacenter L2 networks drive outbound transmission that races with bearer teardown in tipc_disable_l2_media.\nAC:L - The UAF window is a race where attackers control both sides by flooding TIPC Ethernet traffic while bearer disable runs and by concurrently triggering bearer teardown; syzbot reliably reproduced this without attacker-uncontrollable timing.\nPR:N - An unauthenticated remote attacker only needs to send TIPC L2 frames on a segment with an active bearer; bearer_disable teardown during cluster failover, netdev unregister, or node shutdown creates the required concurrent disable without attacker-local privileges.\nUI:N - No victim user action is required; exploitation is triggered by remote protocol traffic concurrent with automated or administrative bearer/interface teardown events.\nS:U - Impact is kernel slab memory corruption and potential privilege escalation within the same kernel security boundary, not a cross-VM or cross-namespace escape.\nC:H - Slab use-after-free of a net_device structure via ipvlan_hard_header enables reading freed kernel heap memory and can be leveraged for arbitrary kernel memory disclosure.\nI:H - UAF on net_device during dev_hard_header allows heap grooming and control of freed object contents, enabling arbitrary kernel writes and potential code execution.\nA:H - The UAF causes kernel oops/panic (as reported by syzbot in ipvlan_hard_header) and can be triggered repeatedly to deny service on cluster nodes."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:45:03.215Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-74255","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T18:51:21.997322Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T18:55:27.929Z"}}]}}}