UNKNOWN NVD
CVE-2026-98568
In the Linux kernel, the following vulnerability has been resolved: vxlan: use one headroom snapshot for neighbour replies vxlan_na_create() samples LL_RESERV
In the Linux kernel, the following vulnerability has been resolved:
vxlan: use one headroom snapshot for neighbour replies
vxlan_na_create() samples LL_RESERVED_SPACE() to size the reply skb and then
samples it again to reserve headroom. A concurrent vxlan_changelink() can
update needed_headroom between the two reads, creating a TOCTOU race. The
second value can exceed the allocation and make the Ethernet header write out
of bounds.
The race is reproducible on the unpatched kernel. It occurred when
vxlan_na_create() generated a neighbour reply while vxlan_changelink() changed
the link headroom. KASAN caught a four-byte write two bytes beyond a 704-byte
skbuff_small_head allocation.
Snapshot the headroom once and use that value for both allocation and
reservation.
References
- https://git.kernel.org/stable/c/315d42ca39f69846662961c25dcf2bb07c350d14
- https://git.kernel.org/stable/c/45a67662bf8ce3aa5643accf98d328dfbb47eaf6
- https://git.kernel.org/stable/c/481506a756dcd828ef42391cb08f38d8d96d38fc
- https://git.kernel.org/stable/c/a3c5eb6e382dd426a5e7eb08608897ed57167ff7
- https://git.kernel.org/stable/c/ff022fd9d0f0282c575e11778b96bd1b637503eb
This unknown severity vulnerability was published on 2026-10-18 via NVD.
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