# 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.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Jun 2026
- **Updated:** 15 Oct 2026
- **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, ROOT-OS-DEBIAN-13-CVE-2026-46321, ROOT-OS-UBUNTU-2204-CVE-2026-46321, ROOT-OS-UBUNTU-2404-CVE-2026-46321, UBUNTU-CVE-2026-46321

## 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: Linux kernel.

## How do I fix CVE-2026-46321?

Apply the vendor's patch.

## 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

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46321 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-46321 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-46321/ (Markdown: https://insights.sbomify.com/CVE-2026-46321/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46321
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46321
- OSV: https://osv.dev/vulnerability/CVE-2026-46321

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46321/
Summaries are generated and may contain mistakes; the official description above is the record.