CVE-2026-98568
Published: October 21, 2026Last modified: October 21, 2026
Description
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.
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | linux-lts | Vulnerable (6.1.189-r0) |
| 25 LTS | linux-lts | Fixed (6.12.112-r0) | |
| Stream | linux-lts | Fixed (6.18.55-r0) |
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