CVE-2026-74743UAF crítico en el controlador macvlan del kernel Linux
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.
Ver en NVDAnálisis
A critical memory corruption vulnerability (use-after-free) has been identified in the Linux kernel macvlan driver. This affects systems using macvlan for container networking or virtualization, especially when combined with tunnels, IPsec, or WireGuard, potentially leading to system instability or exploitation.
Roles relevantes
Severidad
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HEPSS
Sin puntaje EPSS aún (CVE muy reciente).
Descripción técnica
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.
Referencias
- https://git.kernel.org/stable/c/28afc87bd8da0b3348bbbd834c8a89e83712cf5e
- 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/cef51860becd9700217c81732ca1eb1ea6ed6fe1