CVE-2026-72019

/// Technical description

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.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References