CVE-2026-46321 tun: free page on short-frame rejection in tun_xdp_one()
A local attacker can exhaust host memory and cause a denial of service by triggering a page leak in the Linux kernel's tun driver via short frames.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-46321?
CVE-2026-46321 is a high-severity memory corruption vulnerability in Linux kernel, published on 9 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-46321?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46321?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-46321 being exploited?
There is no known exploitation of CVE-2026-46321 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-89675, BELL-CVE-2026-46321, DEBIAN-CVE-2026-46321, GHSA-3qqh-vm6g-ghw6, ROOT-OS-DEBIAN-11-CVE-2026-46321, ROOT-OS-DEBIAN-12-CVE-2026-46321 and 4 more.