{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74695", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.926Z", "datePublished": "2026-08-22T15:32:57.756Z", "dateUpdated": "2026-10-21T12:46:10.628Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:46:10.628Z" }, "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." } ], "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/netfilter/nf_flow_table_ip.c" ], "versions": [ { "version": "2a79fd3908acd88e6cb0e620c314d7b1fee56a02", "lessThan": "4db3b48a966ed479b99cc8319ea9e46d4f7c703b", "status": "affected", "versionType": "git" }, { "version": "2a79fd3908acd88e6cb0e620c314d7b1fee56a02", "lessThan": "274f544a32c08638ee887f2e27e3235b6b1237d4", "status": "affected", "versionType": "git" }, { "version": "2a79fd3908acd88e6cb0e620c314d7b1fee56a02", "lessThan": "12afa450a6a6c0cce2c42b7545a9958f62d8a00c", "status": "affected", "versionType": "git" }, { "version": "2a79fd3908acd88e6cb0e620c314d7b1fee56a02", "lessThan": "538e67e8c7889cf5f93951f5309d1bcb41f86036", "status": "affected", "versionType": "git" }, { "version": "2a79fd3908acd88e6cb0e620c314d7b1fee56a02", "lessThan": "8aecf0bbcc72605592134c917c222207d8f63ab0", "status": "affected", "versionType": "git" }, { "version": "b4b1adf2e66ecc7125c4117e7aad9ff61e2cfd27", "status": "affected", "versionType": "git" }, { "version": "209dedf806d31095968f54323dbe62525b077b33", "status": "affected", "versionType": "git" }, { "version": "4.16.15", "lessThan": "4.17", "status": "affected", "versionType": "semver" }, { "version": "4.17.1", "lessThan": "4.18", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/netfilter/nf_flow_table_ip.c" ], "versions": [ { "version": "4.18", "status": "affected" }, { "version": "0", "lessThan": "4.18", "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": "6.18.45", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.9", "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": "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" } ] } ] } ], "references": [ { "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" } ], "title": "netfilter: nf_flow_table: drop existing skb dst before skb_dst_set_noref()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "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" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:16:09.664Z" } } ] } }