CVE-2026-46321 – tun: free page on short-frame rejection in tun_xdp_one()

CVE ID :CVE-2026-46321

Published : June 9, 2026, 12:11 p.m. | 24 minutes ago

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.

Severity: 0.0 | NA

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