{"id":"CVE-2026-74695","state":"PUBLISHED","title":"netfilter: nf_flow_table: drop existing skb dst before skb_dst_set_noref()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_flow_table: drop existing skb dst before skb_dst_set_noref()\n\nIncoming skbs passing through netfilter flowtable offload hooks (or XFRM\noffload path) might already carry a ref-counted dst_entry assigned during\nearlier RX or routing steps.\n\nCalling skb_dst_set_noref() when skb already holds a ref-counted dst\noverwrites skb->_skb_refdst, leaking the previous dst_entry reference\ncount and triggering a DEBUG_NET_WARN_ON_ONCE assertion in\nskb_dst_check_unset():\n\n  WARNING: at skb_dst_check_unset include/linux/skbuff.h:1170\n  WARNING: at skb_dst_set_noref include/linux/skbuff.h:1234\n  WARNING: at nf_flow_offload_ip_hook+0xf6c/0x2b60 net/netfilter/nf_flow_table_ip.c:864\n\nDrop any existing dst_entry reference with skb_dst_drop(skb) before\nsetting the non-referenced flowtable destination.","publishedAt":"2026-08-22T15:32:57.756Z","updatedAt":"2026-10-30T12:30:19.575Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"763f59b72ddaf18d0750d53083a74355f6c003c8","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"4db3b48a966ed479b99cc8319ea9e46d4f7c703b","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"274f544a32c08638ee887f2e27e3235b6b1237d4","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"12afa450a6a6c0cce2c42b7545a9958f62d8a00c","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"538e67e8c7889cf5f93951f5309d1bcb41f86036","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"8aecf0bbcc72605592134c917c222207d8f63ab0","versionType":"git"},{"version":"b4b1adf2e66ecc7125c4117e7aad9ff61e2cfd27","status":"affected","versionType":"git"},{"version":"209dedf806d31095968f54323dbe62525b077b33","status":"affected","versionType":"git"},{"version":"4.16.15","status":"affected","lessThan":"4.17","versionType":"semver"},{"version":"4.17.1","status":"affected","lessThan":"4.18","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_flow_table_ip.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.18","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","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_ip.c"]}],"references":["https://git.kernel.org/stable/c/763f59b72ddaf18d0750d53083a74355f6c003c8","https://git.kernel.org/stable/c/4db3b48a966ed479b99cc8319ea9e46d4f7c703b","https://git.kernel.org/stable/c/274f544a32c08638ee887f2e27e3235b6b1237d4","https://git.kernel.org/stable/c/12afa450a6a6c0cce2c42b7545a9958f62d8a00c","https://git.kernel.org/stable/c/538e67e8c7889cf5f93951f5309d1bcb41f86036","https://git.kernel.org/stable/c/8aecf0bbcc72605592134c917c222207d8f63ab0"],"weaknesses":[],"ingestedAt":"2026-10-30T12:48:04.825Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74695.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74695","state":"PUBLISHED","datePublished":"2026-08-22T15:32:57.756Z","dateUpdated":"2026-10-30T12:30:19.575Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.926Z"},"containers":{"cna":{"title":"netfilter: nf_flow_table: drop existing skb dst before skb_dst_set_noref()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_flow_table: drop existing skb dst before skb_dst_set_noref()\n\nIncoming skbs passing through netfilter flowtable offload hooks (or XFRM\noffload path) might already carry a ref-counted dst_entry assigned during\nearlier RX or routing steps.\n\nCalling skb_dst_set_noref() when skb already holds a ref-counted dst\noverwrites skb->_skb_refdst, leaking the previous dst_entry reference\ncount and triggering a DEBUG_NET_WARN_ON_ONCE assertion in\nskb_dst_check_unset():\n\n  WARNING: at skb_dst_check_unset include/linux/skbuff.h:1170\n  WARNING: at skb_dst_set_noref include/linux/skbuff.h:1234\n  WARNING: at nf_flow_offload_ip_hook+0xf6c/0x2b60 net/netfilter/nf_flow_table_ip.c:864\n\nDrop any existing dst_entry reference with skb_dst_drop(skb) before\nsetting the non-referenced flowtable destination."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"763f59b72ddaf18d0750d53083a74355f6c003c8","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"4db3b48a966ed479b99cc8319ea9e46d4f7c703b","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"274f544a32c08638ee887f2e27e3235b6b1237d4","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"12afa450a6a6c0cce2c42b7545a9958f62d8a00c","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"538e67e8c7889cf5f93951f5309d1bcb41f86036","versionType":"git"},{"version":"2a79fd3908acd88e6cb0e620c314d7b1fee56a02","status":"affected","lessThan":"8aecf0bbcc72605592134c917c222207d8f63ab0","versionType":"git"},{"version":"b4b1adf2e66ecc7125c4117e7aad9ff61e2cfd27","status":"affected","versionType":"git"},{"version":"209dedf806d31095968f54323dbe62525b077b33","status":"affected","versionType":"git"},{"version":"4.16.15","status":"affected","lessThan":"4.17","versionType":"semver"},{"version":"4.17.1","status":"affected","lessThan":"4.18","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netfilter/nf_flow_table_ip.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.18","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","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_ip.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/763f59b72ddaf18d0750d53083a74355f6c003c8"},{"url":"https://git.kernel.org/stable/c/4db3b48a966ed479b99cc8319ea9e46d4f7c703b"},{"url":"https://git.kernel.org/stable/c/274f544a32c08638ee887f2e27e3235b6b1237d4"},{"url":"https://git.kernel.org/stable/c/12afa450a6a6c0cce2c42b7545a9958f62d8a00c"},{"url":"https://git.kernel.org/stable/c/538e67e8c7889cf5f93951f5309d1bcb41f86036"},{"url":"https://git.kernel.org/stable/c/8aecf0bbcc72605592134c917c222207d8f63ab0"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The bug fires in nf_flow_offload_ip_hook on NF_NETDEV_INGRESS when remotely sourced IPv4/IPv6 packets matching an offloaded flow are received on nftables flowtable-bound interfaces, not via netlink configuration APIs.\nAC:L - Once a flowtable ingress hook and offloaded TCP/UDP flow exist, an attacker can reliably send matching traffic that reaches FLOW_OFFLOAD_XMIT_NEIGH or the XFRM offload path with a ref-counted skb dst; syzbot reproduced this without uncontrollable races.\nPR:N - Exploitation requires only sending network traffic through an already deployed nftables flow-offload path on an ingress device; no local account, authentication, or CAP_NET_ADMIN on the victim is needed to trigger the leak.\nUI:N - No victim interaction is required beyond normal network delivery; packets are processed automatically in softirq on the netdev ingress netfilter hook without opening files or mounting filesystems.\nS:U - Impact is confined to kernel refcount imbalance and availability degradation on the affected host; this is standard in-kernel compromise territory, not a VM escape, IOMMU bypass, or other cross-authority scope change.\nC:N - The flaw leaks a dst_entry reference by overwriting skb->_skb_refdst without releasing the prior dst; it does not expose kernel memory or provide an arbitrary read primitive.\nI:N - No unauthorized data modification occurs; the skb is forwarded using the intended flowtable destination while the previous dst reference is orphaned, not corrupted into a controllable write primitive.\nA:H - Each matching packet leaks a dst_entry refcount on the flowtable fast path, enabling sustained unauthenticated remote memory exhaustion on high-volume routers; CONFIG_DEBUG_NET builds also emit WARN_ON_ONCE during the overwrite."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:30:19.575Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.18.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"7.1.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16.15"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.17.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-74695","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T19:14:42.839344Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:16:09.664Z"}}]}}}