In the Linux kernel, the following vulnerability has been resolved: vxlan: validate ND option lengths in vxlan_na_create vxlan_na_create() walks ND options according to option-provided lengths. A malformed option can make the parser advance beyond the computed option span or use a too-short source LLADDR option payload. Validate option lengths against the remaining NS option area before advancing, and only read source LLADDR when the option is large enough for an Ethernet address.

A flaw was found in the Linux kernel's Virtual Extensible LAN (VXLAN) implementation. A remote attacker could exploit this vulnerability by sending specially crafted Neighbor Discovery (ND) options to the `vxlan_na_create` function. This could cause the parser to read beyond the intended memory boundaries or use an incorrectly sized source Link-Layer Address (LLADDR) option payload, potentially leading to memory corruption and system instability or a denial of service.

VXLAN neighbor-advertisement construction must bound ND option lengths before parsing. Red Hat recommends patched kernels on VXLAN deployments; unload `vxlan` where overlays are unused. To mitigate this issue, prevent the vxlan module from being loaded. See https://access.redhat.com/solutions/41278 for instructions. Red Hat Enterprise Linux 10 Fix deferred kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Fix deferred kernel Red Hat Enterprise Linux 9 Fix deferred kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-31738 https://nvd.nist.gov/vuln/detail/CVE-2026-31738 https://lore.kernel.org/linux-cve-announce/2026050138-CVE-2026-31738-7d4e@gregkh/T