CVE-2026-46321

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

tun: free page on short-frame rejection in tun_xdp_one()

tun_xdp_one() returns -EINVAL on a frame shorter than ETH_HLEN without

freeing the page that vhost_net_build_xdp() allocated for it.

tun_sendmsg() discards that -EINVAL and still returns total_len, so

vhost_tx_batch() takes the success path and never frees the page; each

short frame in a batch leaks one page-frag chunk.

A local process that can open /dev/net/tun and /dev/vhost-net can hit

this path: it attaches a tun/tap device as the vhost-net backend and

feeds TX descriptors whose length minus the virtio-net header is below

ETH_HLEN. Each kick leaks the page-frag chunks for that batch, and a

tight submission loop exhausts host memory and triggers an OOM panic.

Free the page before returning -EINVAL, matching the XDP-program error

path in the same function.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References