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CVE-2026-74667

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

Description (CNA)

In 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.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 before 1e43a1d66615f411d427f9df1f46dd049d9e3681; affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 before 4057853a91fb796c4f47c7d1baf1aa085394148e; affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 before 2610ed4e86a4590234a9d70518c469751c5af231; affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 before b47ba8fe6e1d2df8c92048de5afafd059447dc30; affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 before 284f3e7a3f1a743fdf89e304fd1f19d5ffcff46d; affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 before 971aa7d99242bbf09513e27b7a243f0b29ff23ae; affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 before fdd4d7d52358a58e351dd9d82530c04eba8ccd7a; affected 75c65772c3d18447d62d3aca5f91b06c16cc25e4 before c2707480cfbf19c7619acc9c089d17f20869821f
Linux / Linuxaffected 5.1; unaffected 0 before 5.1; unaffected 5.10.265 through 5.10.*; unaffected 5.15.216 through 5.15.*; unaffected 6.1.183 through 6.1.*; unaffected 6.6.152 through 6.6.*; unaffected 6.12.104 through 6.12.*; unaffected 6.18.45 through 6.18.*; unaffected 7.1.9 through 7.1.*; unaffected 7.2 through *

CWE

No CWE identifiers supplied.

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.