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CVE-2026-72019

macsec: don't read an unset MAC header in macsec_encrypt() PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: macsec: don't read an unset MAC header in macsec_encrypt() macsec_encrypt() reads the Ethernet header via eth_hdr(skb) (skb->head + skb->mac_header) to memmove() the 12 source/destination MAC bytes forward and make room for the SecTAG. On the AF_PACKET SOCK_RAW + PACKET_QDISC_BYPASS transmit path the skb reaches the macsec ndo_start_xmit() with the MAC header unset, so eth_hdr(skb) resolves to skb->head + (u16)~0 and the read is out of bounds: a 12-byte heap over-read that is also emitted on the wire as the frame's outer source/destination MAC. KASAN reports a slab-out-of-bounds read in macsec_start_xmit() on 6.0; on current mainline a CONFIG_DEBUG_NET build flags it as an unset mac header in skb_mac_header(). On the TX path the L2 header is at skb->data, so use skb_eth_hdr(), added by commit 96cc4b69581d ("macvlan: do not assume mac_header is set in macvlan_broadcast()") for exactly this purpose.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected c09440f7dcb304002dfced8c0fea289eb25f2da0 before b6cec6187b8632423cd99a94fd5e5ba165fa2a33; affected c09440f7dcb304002dfced8c0fea289eb25f2da0 before 3adea1b1c04b57e08a5c12a1f42483760581ce61; affected c09440f7dcb304002dfced8c0fea289eb25f2da0 before dc9ffa1905e72f026d080880a2e4cfc42aa91000; affected c09440f7dcb304002dfced8c0fea289eb25f2da0 before f21fa533a3ed15ada74106aac4b9ddd078fc6b7a; affected c09440f7dcb304002dfced8c0fea289eb25f2da0 before e17a42199824973cd8212e95b21ffadf4114a21b; affected c09440f7dcb304002dfced8c0fea289eb25f2da0 before 2cf10d042562283ff4ae97c02d0993d4f1b5ea29; affected c09440f7dcb304002dfced8c0fea289eb25f2da0 before c39087ad0b97fc11a3b058dfc8db9fd370762cb9; affected c09440f7dcb304002dfced8c0fea289eb25f2da0 before f5089008f90c0a7c5520dff3934e0af00adf322d
Linux / Linuxaffected 4.6; unaffected 0 before 4.6; unaffected 5.10.265 through 5.10.*; unaffected 5.15.216 through 5.15.*; unaffected 6.1.178 through 6.1.*; unaffected 6.6.145 through 6.6.*; unaffected 6.12.97 through 6.12.*; unaffected 6.18.40 through 6.18.*; unaffected 7.1.5 through 7.1.*; unaffected 7.2 through *

CWE

No CWE identifiers supplied.

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.