net/packet: reset the MAC header on the packet-socket transmit path

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74667
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:40 UTC
Updated2026-08-22 16:16:40 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/packet: reset the MAC header on the packet-socket transmit path packet_parse_headers() resets the MAC header only for a SOCK_RAW frame whose socket did not bind a protocol. A protocol-bound SOCK_RAW socket, any SOCK_DGRAM frame, and the legacy SOCK_PACKET path therefore leave skb->mac_header unset here. For frames sent via __dev_queue_xmit() this is harmless: it resets the MAC header unconditionally. But the packet-socket PACKET_QDISC_BYPASS path uses dev_direct_xmit(), which does not, so the frame reaches ndo_start_xmit() with the MAC header unset. A driver that reads eth_hdr(skb) on transmit then dereferences skb->head + (u16)~0, an out-of-bounds access ~64 KiB past the head -- the same class fixed for one consumer in commit f5089008f90c ("macsec: do not read an unset MAC header in macsec_encrypt()"). packet_parse_headers() runs only on the transmit path, where skb->data points at the start of the L2 header for every packet-socket type regardless of its length: SOCK_RAW and SOCK_PACKET carry a user-supplied header and SOCK_DGRAM has one built by dev_hard_header(). Reset the MAC header unconditionally, mirroring __dev_queue_xmit(), so the frame is anchored on the bypass path too. Found by 0sec (https://0sec.ai) using automated source analysis; verified against source and matched to the macsec KASAN report in f5089008f90c. Compile-tested.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 1e43a1d66615f411d427f9df1f46dd049d9e3681 git Not specified
CNA Linux Linux affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 4057853a91fb796c4f47c7d1baf1aa085394148e git Not specified
CNA Linux Linux affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 2610ed4e86a4590234a9d70518c469751c5af231 git Not specified
CNA Linux Linux affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 b47ba8fe6e1d2df8c92048de5afafd059447dc30 git Not specified
CNA Linux Linux affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 284f3e7a3f1a743fdf89e304fd1f19d5ffcff46d git Not specified
CNA Linux Linux affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 971aa7d99242bbf09513e27b7a243f0b29ff23ae git Not specified
CNA Linux Linux affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 fdd4d7d52358a58e351dd9d82530c04eba8ccd7a git Not specified
CNA Linux Linux affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 c2707480cfbf19c7619acc9c089d17f20869821f git Not specified
CNA Linux Linux affected 5.1 Not specified
CNA Linux Linux unaffected 5.1 semver Not specified
CNA Linux Linux unaffected 5.10.265 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.152 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.104 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/2610ed4e86a4590234a9d70518c469751c5af231 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/284f3e7a3f1a743fdf89e304fd1f19d5ffcff46d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c2707480cfbf19c7619acc9c089d17f20869821f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1e43a1d66615f411d427f9df1f46dd049d9e3681 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/971aa7d99242bbf09513e27b7a243f0b29ff23ae 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4057853a91fb796c4f47c7d1baf1aa085394148e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fdd4d7d52358a58e351dd9d82530c04eba8ccd7a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b47ba8fe6e1d2df8c92048de5afafd059447dc30 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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