{"cve":"CVE-2026-74667","nvd":{"published":"2026-08-22T16:16:40.580","modified":"2026-10-16T20:17:50.750","status":"Received","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/1e43a1d66615f411d427f9df1f46dd049d9e3681","https://git.kernel.org/stable/c/2610ed4e86a4590234a9d70518c469751c5af231","https://git.kernel.org/stable/c/284f3e7a3f1a743fdf89e304fd1f19d5ffcff46d","https://git.kernel.org/stable/c/4057853a91fb796c4f47c7d1baf1aa085394148e","https://git.kernel.org/stable/c/971aa7d99242bbf09513e27b7a243f0b29ff23ae"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:49:38.260478770+00:00"},"epss":{"cve":"CVE-2026-74667","score":0.00136,"percentile":0.02979,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}