# CVE-2026-64552: virtio-net: fix len check in receive_big()

> A malicious virtio backend can trigger an out-of-bounds write and NULL dereference in the Linux kernel's virtio-net driver, potentially leading to code execution or system crash.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 27 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-94029, BELL-CVE-2026-64552, DEBIAN-CVE-2026-64552, GHSA-6c34-77j2-7g8c, ROOT-OS-DEBIAN-12-CVE-2026-64552, UBUNTU-CVE-2026-64552

## What is CVE-2026-64552?

CVE-2026-64552 is a high-severity memory corruption vulnerability in Linux, published on 27 Jul 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:

virtio-net: fix len check in receive_big()

receive_big() bounds the device-announced length by
(big_packets_num_skbfrags + 1) * PAGE_SIZE.  That is still too loose:
add_recvbuf_big() sets sg[1] to start at offset
sizeof(struct padded_vnet_hdr) into the first page, so the chain
actually carries hdr_len + (PAGE_SIZE - sizeof(padded_vnet_hdr)) +
big_packets_num_skbfrags * PAGE_SIZE bytes -- 20 bytes less than the
check allows for the common hdr_len == 12 case.

A malicious virtio backend can announce a len in that gap.  page_to_skb()
then walks one frag past the page chain, storing a NULL page->private
into skb_shinfo()->frags[MAX_SKB_FRAGS], which is both an out-of-bounds
write past the static frag array and a NULL frag handed up the rx path.

Bound len by the size add_recvbuf_big() actually advertised.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-64552?


## How do I fix CVE-2026-64552?

Apply the vendor's patch.

## Is CVE-2026-64552 being exploited?

There is no known exploitation of CVE-2026-64552 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64552 and fix it if it is affected.

What it is: CVE-2026-64552 is a high-severity memory corruption vulnerability in Linux, published on 27 Jul 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-2026-64552 in the wild and no public exploit code.

Affected product: Linux. 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-2026-64552/ (Markdown: https://insights.sbomify.com/CVE-2026-64552/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64552
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64552
- OSV: https://osv.dev/vulnerability/CVE-2026-64552

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64552/
Summaries are generated and may contain mistakes; the official description above is the record.