{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74667", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.924Z", "datePublished": "2026-08-22T15:32:38.862Z", "dateUpdated": "2026-10-16T19:16:08.261Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-25T05:41:21.641Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/packet: reset the MAC header on the packet-socket transmit path\n\npacket_parse_headers() resets the MAC header only for a SOCK_RAW frame\nwhose socket did not bind a protocol. A protocol-bound SOCK_RAW socket,\nany SOCK_DGRAM frame, and the legacy SOCK_PACKET path therefore leave\nskb->mac_header unset here.\n\nFor frames sent via __dev_queue_xmit() this is harmless: it resets the\nMAC header unconditionally. But the packet-socket PACKET_QDISC_BYPASS\npath uses dev_direct_xmit(), which does not, so the frame reaches\nndo_start_xmit() with the MAC header unset. A driver that reads\neth_hdr(skb) on transmit then dereferences skb->head + (u16)~0, an\nout-of-bounds access ~64 KiB past the head -- the same class fixed for\none consumer in commit f5089008f90c (\"macsec: do not read an unset MAC\nheader in macsec_encrypt()\").\n\npacket_parse_headers() runs only on the transmit path, where skb->data\npoints at the start of the L2 header for every packet-socket type\nregardless of its length: SOCK_RAW and SOCK_PACKET carry a user-supplied\nheader and SOCK_DGRAM has one built by dev_hard_header(). Reset the MAC\nheader unconditionally, mirroring __dev_queue_xmit(), so the frame is\nanchored on the bypass path too.\n\nFound by 0sec (https://0sec.ai) using automated source analysis;\nverified against source and matched to the macsec KASAN report in\nf5089008f90c. Compile-tested." } ], "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 flaw is reached only via local AF_PACKET transmit syscalls (sendmsg on SOCK_DGRAM/bound SOCK_RAW with PACKET_QDISC_BYPASS); remote network input cannot trigger packet_parse_headers() on this TX path.\nAC:L - The attacker controls socket type, enables PACKET_QDISC_BYPASS via setsockopt, selects a vulnerable netdev (macsec/macvlan/tap), and sends frames to reliably hit dev_direct_xmit() without races or external victim state.\nPR:L - packet_create() requires CAP_NET_RAW, which unprivileged users commonly obtain inside user+network namespaces (unshare -Urn) per kernel capability rules, not solely real root in the init namespace.\nUI:N - Exploitation requires only the attacker opening a packet socket, enabling bypass, and transmitting; no victim user action such as opening files or mounting filesystems is needed.\nS:U - Impact is kernel heap/slab disclosure and transmit-time corruption within the same kernel security authority; it is not a VM escape, IOMMU bypass, or other cross-boundary scope change.\nC:H - Unset mac_header makes eth_hdr(skb) a large out-of-bounds kernel memory read (~64 KiB past skb->head); macsec KASAN confirmed slab data leakage and bytes can be emitted on the wire in the frame.\nI:H - Affected TX drivers consume the bogus eth_hdr() pointer to modify skbs (e.g., macsec memmove of OOB MAC bytes into the frame, vxlan header rewrites), giving attacker-influenced corruption beyond a pure read.\nA:H - The invalid mac_header dereference can fault or trigger KASAN/driver failures during ndo_start_xmit(), causing kernel oops/panic or repeated transmit failure on the bypass path." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/packet/af_packet.c" ], "versions": [ { "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4", "lessThan": "1e43a1d66615f411d427f9df1f46dd049d9e3681", "status": "affected", "versionType": "git" }, { "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4", "lessThan": "4057853a91fb796c4f47c7d1baf1aa085394148e", "status": "affected", "versionType": "git" }, { "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4", "lessThan": "2610ed4e86a4590234a9d70518c469751c5af231", "status": "affected", "versionType": "git" }, { "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4", "lessThan": "b47ba8fe6e1d2df8c92048de5afafd059447dc30", "status": "affected", "versionType": "git" }, { "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4", "lessThan": "284f3e7a3f1a743fdf89e304fd1f19d5ffcff46d", "status": "affected", "versionType": "git" }, { "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4", "lessThan": "971aa7d99242bbf09513e27b7a243f0b29ff23ae", "status": "affected", "versionType": "git" }, { "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4", "lessThan": "fdd4d7d52358a58e351dd9d82530c04eba8ccd7a", "status": "affected", "versionType": "git" }, { "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4", "lessThan": "c2707480cfbf19c7619acc9c089d17f20869821f", "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/packet/af_packet.c" ], "versions": [ { "version": "5.1", "status": "affected" }, { "version": "0", "lessThan": "5.1", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.265", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.152", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.104", "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": "5.1", "versionEndExcluding": "5.10.265" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.1", "versionEndExcluding": "5.15.216" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.1", "versionEndExcluding": "6.1.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.1", "versionEndExcluding": "6.6.152" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.1", "versionEndExcluding": "6.12.104" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.1", "versionEndExcluding": "6.18.45" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.1", "versionEndExcluding": "7.1.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.1", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/1e43a1d66615f411d427f9df1f46dd049d9e3681" }, { "url": "https://git.kernel.org/stable/c/4057853a91fb796c4f47c7d1baf1aa085394148e" }, { "url": "https://git.kernel.org/stable/c/2610ed4e86a4590234a9d70518c469751c5af231" }, { "url": "https://git.kernel.org/stable/c/b47ba8fe6e1d2df8c92048de5afafd059447dc30" }, { "url": "https://git.kernel.org/stable/c/284f3e7a3f1a743fdf89e304fd1f19d5ffcff46d" }, { "url": "https://git.kernel.org/stable/c/971aa7d99242bbf09513e27b7a243f0b29ff23ae" }, { "url": "https://git.kernel.org/stable/c/fdd4d7d52358a58e351dd9d82530c04eba8ccd7a" }, { "url": "https://git.kernel.org/stable/c/c2707480cfbf19c7619acc9c089d17f20869821f" } ], "title": "net/packet: reset the MAC header on the packet-socket transmit path", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-74667", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:14:14.644201Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:16:08.261Z" } } ] } }