CVE-2026-74743

Description

In the Linux kernel, the following vulnerability has been resolved: macvlan: inherit needed_headroom and needed_tailroom from lowerdev macvlan devices inherit hard_header_len from lowerdev during macvlan_init(), but leave needed_headroom and needed_tailroom set to 0. When the underlying lowerdev requires extra headroom or tailroom for headers/trailers (e.g. macsec, ipsec, wireguard, tunnels, or veth with rx headroom), upper layers calculating packet headroom and tailroom fail to reserve sufficient space. This can result in reallocation overhead, skb headroom underflows, or KASAN slab-use-after-free crashes when dev_hard_header() / macvlan_hard_header() prepends header data or when lower devices append tailroom. Fix this by: 1. Inheriting needed_headroom and needed_tailroom from lowerdev in macvlan_init(). 2. Propagating needed_headroom and needed_tailroom updates to attached macvlans in macvlan_device_event() when receiving NETDEV_FEAT_CHANGE events.

CVSS 3.1 breakdown

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

References

• https://git.kernel.org/stable/c/28afc87bd8da0b3348bbbd834c8a89e83712cf5e
• https://git.kernel.org/stable/c/7b0eb3e0f363ca79a3af9efd2e87c6258f11da2b
• https://git.kernel.org/stable/c/8cd90e850e434577bf6774778657d26d6995e53f
• https://git.kernel.org/stable/c/8f6a05dbac05725e0786701eb04778c5bdbe4eaa
• https://git.kernel.org/stable/c/96fa90b74385b7f2b0d97251dd43d5ee6ca44668
• https://git.kernel.org/stable/c/bc9a00fb78e32bccc39d763bfd13a450705bac5d
• https://git.kernel.org/stable/c/c2ef3f134b069c54b9cc95cce1a16c38c4939336
• https://git.kernel.org/stable/c/cef51860becd9700217c81732ca1eb1ea6ed6fe1

Frequently asked