{"id":"CVE-2026-74746","state":"PUBLISHED","title":"netfilter: flowtable: publish GC-visible tuple last","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: publish GC-visible tuple last\n\nnf_flow_table_iterate() only treats original-direction tuple nodes as\nowning entries. Publishing the original node first lets GC observe and\nfree a flow while flow_offload_add() is still inserting the reply node.\nPublish the reply node first and the original node last so GC never\nsees a partially installed flow.\n\nKASAN can trigger slab-use-after-free read and write reports in the\nflowtable/rhashtable path (rht_deferred_worker, jhash, flow_offload_del,\nflow_offload_lookup, etc.).","publishedAt":"2026-08-26T14:36:55.963Z","updatedAt":"2026-10-16T19:26:23.781Z","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":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"0a00254585827f1695aa2700114af622ea754cfa","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"be345dcbddb4643a54252b954af974b16eda8f91","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"211ee5d998d92a7d548811939c65942d06c146e4","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"d37917e7bebe078f3c17e47fd6fc1c9f6e8497b2","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"972fdf7c4f5c282a239c88fea614b056c33dc025","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"d9d3050a70efe217e73a0751e55fdae6a7092620","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"d16b71231e65cb05daea2b45701fcf09cef041e7","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"2014ac62df9d45bb9a004a043e85df7be09ed780","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_flow_table_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"5.10.266","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.217","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.184","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.153","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.105","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.46","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.10","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/netfilter/nf_flow_table_core.c"]}],"references":["https://git.kernel.org/stable/c/0a00254585827f1695aa2700114af622ea754cfa","https://git.kernel.org/stable/c/be345dcbddb4643a54252b954af974b16eda8f91","https://git.kernel.org/stable/c/211ee5d998d92a7d548811939c65942d06c146e4","https://git.kernel.org/stable/c/d37917e7bebe078f3c17e47fd6fc1c9f6e8497b2","https://git.kernel.org/stable/c/972fdf7c4f5c282a239c88fea614b056c33dc025","https://git.kernel.org/stable/c/d9d3050a70efe217e73a0751e55fdae6a7092620","https://git.kernel.org/stable/c/d16b71231e65cb05daea2b45701fcf09cef041e7","https://git.kernel.org/stable/c/2014ac62df9d45bb9a004a043e85df7be09ed780"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74746.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74746","state":"PUBLISHED","datePublished":"2026-08-26T14:36:55.963Z","dateUpdated":"2026-10-16T19:26:23.781Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.931Z"},"containers":{"cna":{"title":"netfilter: flowtable: publish GC-visible tuple last","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: publish GC-visible tuple last\n\nnf_flow_table_iterate() only treats original-direction tuple nodes as\nowning entries. Publishing the original node first lets GC observe and\nfree a flow while flow_offload_add() is still inserting the reply node.\nPublish the reply node first and the original node last so GC never\nsees a partially installed flow.\n\nKASAN can trigger slab-use-after-free read and write reports in the\nflowtable/rhashtable path (rht_deferred_worker, jhash, flow_offload_del,\nflow_offload_lookup, etc.)."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"0a00254585827f1695aa2700114af622ea754cfa","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"be345dcbddb4643a54252b954af974b16eda8f91","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"211ee5d998d92a7d548811939c65942d06c146e4","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"d37917e7bebe078f3c17e47fd6fc1c9f6e8497b2","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"972fdf7c4f5c282a239c88fea614b056c33dc025","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"d9d3050a70efe217e73a0751e55fdae6a7092620","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"d16b71231e65cb05daea2b45701fcf09cef041e7","versionType":"git"},{"version":"ac2a66665e231847cab11b8c8e844ce43207dd2e","status":"affected","lessThan":"2014ac62df9d45bb9a004a043e85df7be09ed780","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_flow_table_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"5.10.266","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.217","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.184","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.153","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.105","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.46","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.10","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/netfilter/nf_flow_table_core.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/0a00254585827f1695aa2700114af622ea754cfa"},{"url":"https://git.kernel.org/stable/c/be345dcbddb4643a54252b954af974b16eda8f91"},{"url":"https://git.kernel.org/stable/c/211ee5d998d92a7d548811939c65942d06c146e4"},{"url":"https://git.kernel.org/stable/c/d37917e7bebe078f3c17e47fd6fc1c9f6e8497b2"},{"url":"https://git.kernel.org/stable/c/972fdf7c4f5c282a239c88fea614b056c33dc025"},{"url":"https://git.kernel.org/stable/c/d9d3050a70efe217e73a0751e55fdae6a7092620"},{"url":"https://git.kernel.org/stable/c/d16b71231e65cb05daea2b45701fcf09cef041e7"},{"url":"https://git.kernel.org/stable/c/2014ac62df9d45bb9a004a043e85df7be09ed780"}],"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 - flow_offload_add runs from nft_flow_offload_eval on the FORWARD hook and from tc act_ct during softirq packet processing when remote TCP/UDP traffic creates new offloaded conntrack flows on nftables flowtable routers/gateways, not through netlink configuration APIs.\nAC:L - The attacker controls when flows are offloaded (packet rate/timing) and can race connection teardown so nf_flow_table_gc_run observes a partially installed original tuple while reply insertion is still in progress; both the insert and GC sides of the race are attacker-driven.\nPR:N - On the intended edge-router/OpenWrt deployment, nftables flow offload is an administrator prerequisite; a remote sender needs no local account, authentication, or CAP_NET_ADMIN on the victim to trigger flow_offload_add while forwarding traffic.\nUI:N - Exploitation requires only sending network packets processed automatically on the forwarding or ingress path; no victim must open files, mount filesystems, or take any interactive action beyond normal traffic through the router.\nS:U - Slab use-after-free in the flowtable rhashtable/GC path affects only in-kernel memory on the affected host; this is standard kernel compromise within one security authority, not a VM escape, IOMMU bypass, or cross-boundary sandbox break.\nC:H - The fix commit documents KASAN slab-use-after-free read and write reports in rht_deferred_worker, jhash, flow_offload_del, and flow_offload_lookup; UAF on flow_offload kmem-cache objects enables arbitrary kernel memory disclosure via heap grooming.\nI:H - Freed flow_offload structures remain reachable during concurrent rhashtable insert/remove and deferred worker operations, providing attacker-influenceable heap corruption that can be groomed into arbitrary kernel writes and control-flow hijack.\nA:H - Concurrent GC freeing of a partially inserted flow while flow_offload_add or rhashtable workers still access it causes kernel oops/panic and reliable denial of service; UAF on the flow offload path can crash forwarding routers under sustained malicious traffic."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-27T05:01:07.405Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.10.266"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.15.217"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.1.184"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.6.153"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.12.105"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.18.46"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"7.1.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-74746","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T19:16:14.907909Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:26:23.781Z"}}]}}}