{"id":"CVE-2026-64123","state":"PUBLISHED","title":"net: hsr: defer node table free until after RCU readers","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: hsr: defer node table free until after RCU readers\n\nHSR node-list and node-status generic-netlink operations run under\nrcu_read_lock(). They walk hsr->node_db through hsr_get_next_node() and\nhsr_get_node_data(), but RTM_DELLINK teardown removes the same node table\nwith plain list_del() and frees each node immediately.\n\nThat lets a generic-netlink reader hold a struct hsr_node pointer across\nhsr_dellink(). In a KASAN build, widening the reader window after\nhsr_get_next_node() obtains the node reproduces a slab-use-after-free\nwhen the reader copies node->macaddress_A; the freeing stack is\nhsr_del_nodes() from hsr_dellink().\n\nUse list_del_rcu() and defer the free through the existing\nhsr_free_node_rcu() callback. This matches the lifetime rule used by the\nHSR prune paths, which already delete nodes with list_del_rcu() and\ncall_rcu().","publishedAt":"2026-07-19T15:40:21.161Z","updatedAt":"2026-10-19T20:28:13.256Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/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":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"0ea70fb46940620848c08d9d399455c9e82fecdb","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"c5580114e0492bcd2e0a37613ed4c311e3fa3d4d","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"7713f4aafb577ff49fa67f0488d9c7dddc64d6ce","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"6324423a8e6591f41a16c09a8f9a84e554ac147c","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"48d09dea506de667eb55f939bf98eec721effbdb","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"8c3af18bb0d7c921a5219194037509463eb2ffde","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"aaec7096f9961eb223b5b149abe9495525c205d9","versionType":"git"},{"version":"08523d5a2f4a9e4202e00d282c164d453cabe2d2","status":"affected","versionType":"git"},{"version":"5.2.12","status":"affected","lessThan":"5.3","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/hsr/hsr_framereg.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.3","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/hsr/hsr_framereg.c"]}],"references":["https://git.kernel.org/stable/c/0ea70fb46940620848c08d9d399455c9e82fecdb","https://git.kernel.org/stable/c/8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b","https://git.kernel.org/stable/c/c5580114e0492bcd2e0a37613ed4c311e3fa3d4d","https://git.kernel.org/stable/c/7713f4aafb577ff49fa67f0488d9c7dddc64d6ce","https://git.kernel.org/stable/c/6324423a8e6591f41a16c09a8f9a84e554ac147c","https://git.kernel.org/stable/c/48d09dea506de667eb55f939bf98eec721effbdb","https://git.kernel.org/stable/c/8c3af18bb0d7c921a5219194037509463eb2ffde","https://git.kernel.org/stable/c/aaec7096f9961eb223b5b149abe9495525c205d9"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64123.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64123","state":"PUBLISHED","datePublished":"2026-07-19T15:40:21.161Z","dateUpdated":"2026-10-19T20:28:13.256Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.036Z"},"containers":{"cna":{"title":"net: hsr: defer node table free until after RCU readers","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: hsr: defer node table free until after RCU readers\n\nHSR node-list and node-status generic-netlink operations run under\nrcu_read_lock(). They walk hsr->node_db through hsr_get_next_node() and\nhsr_get_node_data(), but RTM_DELLINK teardown removes the same node table\nwith plain list_del() and frees each node immediately.\n\nThat lets a generic-netlink reader hold a struct hsr_node pointer across\nhsr_dellink(). In a KASAN build, widening the reader window after\nhsr_get_next_node() obtains the node reproduces a slab-use-after-free\nwhen the reader copies node->macaddress_A; the freeing stack is\nhsr_del_nodes() from hsr_dellink().\n\nUse list_del_rcu() and defer the free through the existing\nhsr_free_node_rcu() callback. This matches the lifetime rule used by the\nHSR prune paths, which already delete nodes with list_del_rcu() and\ncall_rcu()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"0ea70fb46940620848c08d9d399455c9e82fecdb","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"c5580114e0492bcd2e0a37613ed4c311e3fa3d4d","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"7713f4aafb577ff49fa67f0488d9c7dddc64d6ce","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"6324423a8e6591f41a16c09a8f9a84e554ac147c","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"48d09dea506de667eb55f939bf98eec721effbdb","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"8c3af18bb0d7c921a5219194037509463eb2ffde","versionType":"git"},{"version":"b9a1e627405d68d475a3c1f35e685ccfb5bbe668","status":"affected","lessThan":"aaec7096f9961eb223b5b149abe9495525c205d9","versionType":"git"},{"version":"08523d5a2f4a9e4202e00d282c164d453cabe2d2","status":"affected","versionType":"git"},{"version":"5.2.12","status":"affected","lessThan":"5.3","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/hsr/hsr_framereg.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.3","versionType":"semver"},{"version":"5.10.259","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/hsr/hsr_framereg.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/0ea70fb46940620848c08d9d399455c9e82fecdb"},{"url":"https://git.kernel.org/stable/c/8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b"},{"url":"https://git.kernel.org/stable/c/c5580114e0492bcd2e0a37613ed4c311e3fa3d4d"},{"url":"https://git.kernel.org/stable/c/7713f4aafb577ff49fa67f0488d9c7dddc64d6ce"},{"url":"https://git.kernel.org/stable/c/6324423a8e6591f41a16c09a8f9a84e554ac147c"},{"url":"https://git.kernel.org/stable/c/48d09dea506de667eb55f939bf98eec721effbdb"},{"url":"https://git.kernel.org/stable/c/8c3af18bb0d7c921a5219194037509463eb2ffde"},{"url":"https://git.kernel.org/stable/c/aaec7096f9961eb223b5b149abe9495525c205d9"}],"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 - Exploitation requires local netlink access: generic-netlink HSR_C_GET_NODE_LIST/HSR_C_GET_NODE_STATUS and rtnetlink RTM_DELLINK. The bug is not reachable via HSR/PRP network frames despite HSR being a network redundancy protocol.\nAC:L - The attacker controls both sides of the race by issuing concurrent GENL node queries and RTM_DELLINK on separate threads; no unpredictable victim state or memory layout is required beyond having an HSR interface configured.\nPR:L - Reliable exploitation requires CAP_NET_ADMIN to delete the HSR device via RTM_DELLINK (and typically to create it); CAP_NET_ADMIN is obtainable by an unprivileged user through user namespaces (unshare -Urn), and the GENL read operations themselves carry no admin-perm flag.\nUI:N - No victim interaction is required; the race is triggered entirely by the attacker's own concurrent netlink operations.\nS:U - Impact is confined to kernel memory corruption and privilege escalation within the same kernel/host security boundary, not a cross-boundary escape such as VM or sandbox breakout.\nC:H - This is a slab use-after-free on struct hsr_node; freed objects can be reallocated and read through fields like macaddress_A/B and block_buf, enabling arbitrary kernel memory disclosure.\nI:H - UAF on a kmalloc'd hsr_node with spinlock and pointer fields (block_buf, seq_blocks) provides standard heap-spray primitives for arbitrary kernel writes and potential code execution.\nA:H - Use-after-free on hsr_node during RCU-protected traversal causes kernel oops/panic even without full exploitation, as confirmed by KASAN on the macaddress_A copy path."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-15T10:08:03.582Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"5.10.259"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"5.15.210"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"6.1.176"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"6.6.143"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"6.12.93"},{"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":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3","versionEndExcluding":"7.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.2.12"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64123","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:36:43.824256Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","lang":"en","type":"CWE","description":"CWE-416 Use After Free"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:28:13.256Z"}}]}}}