CVE-2026-74743
CriticalCVSS 9.8Summary
In the Linux kernel, macvlan interfaces do not inherit needed_headroom and needed_tailroom from the lower device, which can lead to insufficient space reservation for headers and trailers. This results in buffer overflows, headroom underflows, or KASAN slab-use-after-free crashes.
Risk Assessment
The vulnerability could be exploited to cause a system crash or potentially execute code, threatening system stability and security.
Recommendation
Apply the kernel patch that adds inheritance of needed_headroom and needed_tailroom in macvlan and propagates changes on NETDEV_FEAT_CHANGE events.
Original NVD description (English source)
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.