CVE-2026-72404

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-72404", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.925Z", "datePublished": "2026-08-15T05:56:28.124Z", "dateUpdated": "2026-10-30T12:29:17.840Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-30T12:29:17.840Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix UAF in cleanup_bearer() due to premature dst_cache_destroy()\n\nTIPC UDP media bearer teardown calls dst_cache_destroy() on its\nreplicast caches before calling synchronize_net() to wait for\nconcurrent RCU readers (transmitters) to finish:\n\nstatic void cleanup_bearer(struct work_struct *work)\n{\n...\n\tlist_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {\n\t\tdst_cache_destroy(&rcast->dst_cache);\n\t\tlist_del_rcu(&rcast->list);\n\t\tkfree_rcu(rcast, rcu);\n\t}\n...\n\tdst_cache_destroy(&ub->rcast.dst_cache);\n\tudp_tunnel_sock_release(ub->sk);\n\tsynchronize_net();\n...\n}\n\nThis is highly buggy because dst_cache_destroy() immediately frees the\nper-CPU cache memory (free_percpu()) and releases the cached dst\nentries without any synchronization.\n\nIf a concurrent transmitter (e.g., tipc_udp_xmit()) is running on another\nCPU under RCU protection, it can call dst_cache_get() concurrently,\nleading to:\n1. Use-After-Free on the per-CPU cache pointer itself (crash).\n2. \"rcuref - imbalanced put()\" warning if it attempts to release a\n dst that was concurrently released by dst_cache_destroy().\n\nFurthermore, calling kfree(ub) immediately after synchronize_net() without\nclosing the socket first (or waiting after closing it) leaves a window\nwhere a concurrent receiver (tipc_udp_recv()) could start after\nsynchronize_net(), access ub, and suffer a UAF when kfree(ub) runs.\n\nTo fix this, we must defer dst_cache_destroy() and kfree(ub) until after\nwe have ensured that no more readers can see the bearer/socket and all\nexisting readers have finished:\n\n1. Defer rcast entry destruction (both dst_cache_destroy() and kfree())\n to an RCU callback using call_rcu_hurry().\n Using call_rcu_hurry() ensures the dst entries are released quickly.\n\n2. Release the bearer socket using udp_tunnel_sock_release() (stops\n new receive readers).\n\n3. Call synchronize_net() to wait for all outstanding RCU readers\n (both transmit and receive) to finish.\n\n4. Now that it is safe, call dst_cache_destroy() on the main bearer\n cache, and free ub.\n\nNote: 3) and 4) can be changed later in net-next to also use\ncall_rcu_hurry() and get rid of the synchronize_net() latency."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - The UAF is in cleanup_bearer() during UDP bearer teardown, reached only via TIPC genetlink bearer disable (TIPC_NL_BEARER_DISABLE) or network-namespace exit; remote UDP/TIPC peers cannot initiate teardown, so exploitation requires local netlink/netns access even though concurrent xmit/recv may involve network I/O.\nAC:L - An attacker with namespace CAP_NET_ADMIN can script both teardown and concurrent traffic (enable/disable bearer or destroy netns while sending/receiving TIPC UDP on port 6118), controlling both sides of the RCU race; dst_cache_destroy()'s free_percpu() widens the window and syzbot triggered it reliably.\nPR:L - Bearer disable/enable and netns teardown require CAP_NET_ADMIN; TIPC genetlink ops use GENL_UNS_ADMIN_PERM and tipc_genl_family.netnsok=true, so unprivileged users obtain effective net-admin capability via user/network namespaces (unshare -Urn).\nUI:N - Exploitation needs no victim interaction beyond the attacker's own namespace/netlink operations and packet generation; no mount, file open, or other user-directed action is required.\nS:U - The use-after-free corrupts kernel heap memory within the same kernel security domain; impacts are kernel crash or local privilege escalation, not VM escape or cross-security-authority boundary crossing.\nC:H - Premature dst_cache_destroy() frees per-CPU cache memory while concurrent tipc_udp_xmit() may call dst_cache_get() on the freed object, and the post-synchronize_net() recv path dereferences freed udp_bearer, enabling kernel memory disclosure.\nI:H - UAF on dst_cache structures and udp_bearer allows heap shaping and control of freed-object contents, providing primitives for arbitrary kernel writes and potential control-flow hijacking/local privilege escalation.\nA:H - Concurrent use-after-free reliably causes kernel oops/panic (per commit: UAF on per-CPU cache pointer crashes) and can be triggered repeatedly during scripted bearer teardown loops."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/tipc/udp_media.c"], "versions": [{"version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "5a66ca574eee958123ee9d2822683964d42d656a", "status": "affected", "versionType": "git"}, {"version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "6aeb4ba4fb098199e13723cfd04d9a749741f731", "status": "affected", "versionType": "git"}, {"version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "6b0e29f7662c237e717f35dad746efe94715d0da", "status": "affected", "versionType": "git"}, {"version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "3827ff67f9fbecd1086e33d23693ef6a1a9c6c38", "status": "affected", "versionType": "git"}, {"version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "1c8393eefa3cadf4ca0b61119ad1321aa32d3c8c", "status": "affected", "versionType": "git"}, {"version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "7116764ca53ff529335d7ab7c364a69f094b23a5", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/tipc/udp_media.c"], "versions": [{"version": "5.3", "status": "affected"}, {"version": "0", "lessThan": "5.3", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.191", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.114", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.57", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.1.191"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.6.160"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.12.114"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.18.57"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "7.1.5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/5a66ca574eee958123ee9d2822683964d42d656a"}, {"url": "https://git.kernel.org/stable/c/6aeb4ba4fb098199e13723cfd04d9a749741f731"}, {"url": "https://git.kernel.org/stable/c/6b0e29f7662c237e717f35dad746efe94715d0da"}, {"url": "https://git.kernel.org/stable/c/3827ff67f9fbecd1086e33d23693ef6a1a9c6c38"}, {"url": "https://git.kernel.org/stable/c/1c8393eefa3cadf4ca0b61119ad1321aa32d3c8c"}, {"url": "https://git.kernel.org/stable/c/7116764ca53ff529335d7ab7c364a69f094b23a5"}], "title": "tipc: fix UAF in cleanup_bearer() due to premature dst_cache_destroy()", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-72404", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T18:49:02.601623Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T18:55:21.804Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-72404", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T18:49:02.601623Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T18:49:04.586Z"}}], "cna": {"title": "tipc: fix UAF in cleanup_bearer() due to premature dst_cache_destroy()", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 7.8, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:L - The UAF is in cleanup_bearer() during UDP bearer teardown, reached only via TIPC genetlink bearer disable (TIPC_NL_BEARER_DISABLE) or network-namespace exit; remote UDP/TIPC peers cannot initiate teardown, so exploitation requires local netlink/netns access even though concurrent xmit/recv may involve network I/O.\nAC:L - An attacker with namespace CAP_NET_ADMIN can script both teardown and concurrent traffic (enable/disable bearer or destroy netns while sending/receiving TIPC UDP on port 6118), controlling both sides of the RCU race; dst_cache_destroy()'s free_percpu() widens the window and syzbot triggered it reliably.\nPR:L - Bearer disable/enable and netns teardown require CAP_NET_ADMIN; TIPC genetlink ops use GENL_UNS_ADMIN_PERM and tipc_genl_family.netnsok=true, so unprivileged users obtain effective net-admin capability via user/network namespaces (unshare -Urn).\nUI:N - Exploitation needs no victim interaction beyond the attacker's own namespace/netlink operations and packet generation; no mount, file open, or other user-directed action is required.\nS:U - The use-after-free corrupts kernel heap memory within the same kernel security domain; impacts are kernel crash or local privilege escalation, not VM escape or cross-security-authority boundary crossing.\nC:H - Premature dst_cache_destroy() frees per-CPU cache memory while concurrent tipc_udp_xmit() may call dst_cache_get() on the freed object, and the post-synchronize_net() recv path dereferences freed udp_bearer, enabling kernel memory disclosure.\nI:H - UAF on dst_cache structures and udp_bearer allows heap shaping and control of freed-object contents, providing primitives for arbitrary kernel writes and potential control-flow hijacking/local privilege escalation.\nA:H - Concurrent use-after-free reliably causes kernel oops/panic (per commit: UAF on per-CPU cache pointer crashes) and can be triggered repeatedly during scripted bearer teardown loops."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "5a66ca574eee958123ee9d2822683964d42d656a", "versionType": "git"}, {"status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "6aeb4ba4fb098199e13723cfd04d9a749741f731", "versionType": "git"}, {"status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "6b0e29f7662c237e717f35dad746efe94715d0da", "versionType": "git"}, {"status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "3827ff67f9fbecd1086e33d23693ef6a1a9c6c38", "versionType": "git"}, {"status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "1c8393eefa3cadf4ca0b61119ad1321aa32d3c8c", "versionType": "git"}, {"status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "lessThan": "7116764ca53ff529335d7ab7c364a69f094b23a5", "versionType": "git"}], "programFiles": ["net/tipc/udp_media.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "5.3"}, {"status": "unaffected", "version": "0", "lessThan": "5.3", "versionType": "semver"}, {"status": "unaffected", "version": "6.1.191", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.160", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.114", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.57", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "7.1.5", "versionType": "semver", "lessThanOrEqual": "7.1.*"}, {"status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["net/tipc/udp_media.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/5a66ca574eee958123ee9d2822683964d42d656a"}, {"url": "https://git.kernel.org/stable/c/6aeb4ba4fb098199e13723cfd04d9a749741f731"}, {"url": "https://git.kernel.org/stable/c/6b0e29f7662c237e717f35dad746efe94715d0da"}, {"url": "https://git.kernel.org/stable/c/3827ff67f9fbecd1086e33d23693ef6a1a9c6c38"}, {"url": "https://git.kernel.org/stable/c/1c8393eefa3cadf4ca0b61119ad1321aa32d3c8c"}, {"url": "https://git.kernel.org/stable/c/7116764ca53ff529335d7ab7c364a69f094b23a5"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix UAF in cleanup_bearer() due to premature dst_cache_destroy()\n\nTIPC UDP media bearer teardown calls dst_cache_destroy() on its\nreplicast caches before calling synchronize_net() to wait for\nconcurrent RCU readers (transmitters) to finish:\n\nstatic void cleanup_bearer(struct work_struct *work)\n{\n...\n\tlist_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {\n\t\tdst_cache_destroy(&rcast->dst_cache);\n\t\tlist_del_rcu(&rcast->list);\n\t\tkfree_rcu(rcast, rcu);\n\t}\n...\n\tdst_cache_destroy(&ub->rcast.dst_cache);\n\tudp_tunnel_sock_release(ub->sk);\n\tsynchronize_net();\n...\n}\n\nThis is highly buggy because dst_cache_destroy() immediately frees the\nper-CPU cache memory (free_percpu()) and releases the cached dst\nentries without any synchronization.\n\nIf a concurrent transmitter (e.g., tipc_udp_xmit()) is running on another\nCPU under RCU protection, it can call dst_cache_get() concurrently,\nleading to:\n1. Use-After-Free on the per-CPU cache pointer itself (crash).\n2. \"rcuref - imbalanced put()\" warning if it attempts to release a\n dst that was concurrently released by dst_cache_destroy().\n\nFurthermore, calling kfree(ub) immediately after synchronize_net() without\nclosing the socket first (or waiting after closing it) leaves a window\nwhere a concurrent receiver (tipc_udp_recv()) could start after\nsynchronize_net(), access ub, and suffer a UAF when kfree(ub) runs.\n\nTo fix this, we must defer dst_cache_destroy() and kfree(ub) until after\nwe have ensured that no more readers can see the bearer/socket and all\nexisting readers have finished:\n\n1. Defer rcast entry destruction (both dst_cache_destroy() and kfree())\n to an RCU callback using call_rcu_hurry().\n Using call_rcu_hurry() ensures the dst entries are released quickly.\n\n2. Release the bearer socket using udp_tunnel_sock_release() (stops\n new receive readers).\n\n3. Call synchronize_net() to wait for all outstanding RCU readers\n (both transmit and receive) to finish.\n\n4. Now that it is safe, call dst_cache_destroy() on the main bearer\n cache, and free ub.\n\nNote: 3) and 4) can be changed later in net-next to also use\ncall_rcu_hurry() and get rid of the synchronize_net() latency."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.191", "versionStartIncluding": "5.3"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.160", "versionStartIncluding": "5.3"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.114", "versionStartIncluding": "5.3"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18.57", "versionStartIncluding": "5.3"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.1.5", "versionStartIncluding": "5.3"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.2", "versionStartIncluding": "5.3"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-30T12:29:17.840Z"}}}, "cveMetadata": {"cveId": "CVE-2026-72404", "state": "PUBLISHED", "dateUpdated": "2026-10-30T12:29:17.840Z", "dateReserved": "2026-08-09T03:40:39.925Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2026-08-15T05:56:28.124Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/tipc/udp_media.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "5a66ca574eee958123ee9d2822683964d42d656a", "status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "versionType": "git"}, {"lessThan": "6aeb4ba4fb098199e13723cfd04d9a749741f731", "status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "versionType": "git"}, {"lessThan": "6b0e29f7662c237e717f35dad746efe94715d0da", "status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "versionType": "git"}, {"lessThan": "3827ff67f9fbecd1086e33d23693ef6a1a9c6c38", "status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "versionType": "git"}, {"lessThan": "1c8393eefa3cadf4ca0b61119ad1321aa32d3c8c", "status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "versionType": "git"}, {"lessThan": "7116764ca53ff529335d7ab7c364a69f094b23a5", "status": "affected", "version": "e9c1a793210f29f32ee4cf048e04d7d9bb3221cc", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/tipc/udp_media.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.3"}, {"lessThan": "5.3", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.191", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.160", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.114", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.57", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.5", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix UAF in cleanup_bearer() due to premature dst_cache_destroy()\n\nTIPC UDP media bearer teardown calls dst_cache_destroy() on its\nreplicast caches before calling synchronize_net() to wait for\nconcurrent RCU readers (transmitters) to finish:\n\nstatic void cleanup_bearer(struct work_struct *work)\n{\n...\n\tlist_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {\n\t\tdst_cache_destroy(&rcast->dst_cache);\n\t\tlist_del_rcu(&rcast->list);\n\t\tkfree_rcu(rcast, rcu);\n\t}\n...\n\tdst_cache_destroy(&ub->rcast.dst_cache);\n\tudp_tunnel_sock_release(ub->sk);\n\tsynchronize_net();\n...\n}\n\nThis is highly buggy because dst_cache_destroy() immediately frees the\nper-CPU cache memory (free_percpu()) and releases the cached dst\nentries without any synchronization.\n\nIf a concurrent transmitter (e.g., tipc_udp_xmit()) is running on another\nCPU under RCU protection, it can call dst_cache_get() concurrently,\nleading to:\n1. Use-After-Free on the per-CPU cache pointer itself (crash).\n2. \"rcuref - imbalanced put()\" warning if it attempts to release a\n dst that was concurrently released by dst_cache_destroy().\n\nFurthermore, calling kfree(ub) immediately after synchronize_net() without\nclosing the socket first (or waiting after closing it) leaves a window\nwhere a concurrent receiver (tipc_udp_recv()) could start after\nsynchronize_net(), access ub, and suffer a UAF when kfree(ub) runs.\n\nTo fix this, we must defer dst_cache_destroy() and kfree(ub) until after\nwe have ensured that no more readers can see the bearer/socket and all\nexisting readers have finished:\n\n1. Defer rcast entry destruction (both dst_cache_destroy() and kfree())\n to an RCU callback using call_rcu_hurry().\n Using call_rcu_hurry() ensures the dst entries are released quickly.\n\n2. Release the bearer socket using udp_tunnel_sock_release() (stops\n new receive readers).\n\n3. Call synchronize_net() to wait for all outstanding RCU readers\n (both transmit and receive) to finish.\n\n4. Now that it is safe, call dst_cache_destroy() on the main bearer\n cache, and free ub.\n\nNote: 3) and 4) can be changed later in net-next to also use\ncall_rcu_hurry() and get rid of the synchronize_net() latency."}], "id": "CVE-2026-72404", "lastModified": "2026-10-30T13:19:51.223", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-72404", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T18:49:02.601623Z", "version": "2.0.3"}}]}, "published": "2026-08-15T06:22:13.970", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/1c8393eefa3cadf4ca0b61119ad1321aa32d3c8c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/3827ff67f9fbecd1086e33d23693ef6a1a9c6c38"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/5a66ca574eee958123ee9d2822683964d42d656a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6aeb4ba4fb098199e13723cfd04d9a749741f731"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6b0e29f7662c237e717f35dad746efe94715d0da"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7116764ca53ff529335d7ab7c364a69f094b23a5"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: tipc: fix UAF in cleanup_bearer() due to premature dst_cache_destroy()", "id": "2516392", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2516392"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-825", "details": ["In the Linux kernel, the following vulnerability has been resolved:\ntipc: fix UAF in cleanup_bearer() due to premature dst_cache_destroy()\nTIPC UDP media bearer teardown calls dst_cache_destroy() on its\nreplicast caches before calling synchronize_net() to wait for\nconcurrent RCU readers (transmitters) to finish:\nstatic void cleanup_bearer(struct work_struct *work)\n{\n...\nlist_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {\ndst_cache_destroy(&rcast->dst_cache);\nlist_del_rcu(&rcast->list);\nkfree_rcu(rcast, rcu);\n}\n...\ndst_cache_destroy(&ub->rcast.dst_cache);\nudp_tunnel_sock_release(ub->sk);\nsynchronize_net();\n...\n}\nThis is highly buggy because dst_cache_destroy() immediately frees the\nper-CPU cache memory (free_percpu()) and releases the cached dst\nentries without any synchronization.\nIf a concurrent transmitter (e.g., tipc_udp_xmit()) is running on another\nCPU under RCU protection, it can call dst_cache_get() concurrently,\nleading to:\n1. Use-After-Free on the per-CPU cache pointer itself (crash).\n2. \"rcuref - imbalanced put()\" warning if it attempts to release a\ndst that was concurrently released by dst_cache_destroy().\nFurthermore, calling kfree(ub) immediately after synchronize_net() without\nclosing the socket first (or waiting after closing it) leaves a window\nwhere a concurrent receiver (tipc_udp_recv()) could start after\nsynchronize_net(), access ub, and suffer a UAF when kfree(ub) runs.\nTo fix this, we must defer dst_cache_destroy() and kfree(ub) until after\nwe have ensured that no more readers can see the bearer/socket and all\nexisting readers have finished:\n1. Defer rcast entry destruction (both dst_cache_destroy() and kfree())\nto an RCU callback using call_rcu_hurry().\nUsing call_rcu_hurry() ensures the dst entries are released quickly.\n2. Release the bearer socket using udp_tunnel_sock_release() (stops\nnew receive readers).\n3. Call synchronize_net() to wait for all outstanding RCU readers\n(both transmit and receive) to finish.\n4. Now that it is safe, call dst_cache_destroy() on the main bearer\ncache, and free ub.\nNote: 3) and 4) can be changed later in net-next to also use\ncall_rcu_hurry() and get rid of the synchronize_net() latency.", "A flaw was found in the Linux kernel's TIPC UDP media bearer. This vulnerability, a Use-After-Free (UAF) condition, occurs because certain data structures are prematurely destroyed during teardown without proper synchronization with concurrent operations. A local attacker with network access could exploit this race condition, potentially leading to a system crash or memory corruption."], "name": "CVE-2026-72404", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-15T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-72404\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-72404\nhttps://lore.kernel.org/linux-cve-announce/2026081522-CVE-2026-72404-b809@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[e9c1a793210f29f32ee4cf048e04d7d9bb3221cc,1c8393eefa3cadf4ca0b61119ad1321aa32d3c8c)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[e9c1a793210f29f32ee4cf048e04d7d9bb3221cc,7116764ca53ff529335d7ab7c364a69f094b23a5)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "5.3"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,5.3)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "7.2-rc1"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-08-15T11:15:03.436374+00:00", "updated": "2026-08-22T04:30:06.710978+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"], "weaknesses": ["CWE-416", "CWE-825"]}