# CVE-2026-74476: veth: convert frag_list skbs before running XDP

> A flaw in the Linux kernel veth driver causes a crash when processing fragmented packets with XDP, leading to denial of service.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-96458, BELL-CVE-2026-74476, DEBIAN-CVE-2026-74476, GHSA-p72r-vmh2-4xj6, UBUNTU-CVE-2026-74476

## What is CVE-2026-74476?

CVE-2026-74476 is a critical vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

veth: convert frag_list skbs before running XDP

A frag_list skb can reach veth with data_len set but nr_frags zero.
veth_convert_skb_to_xdp_buff() only converts skbs that are shared,
locked, have frags[], or do not have enough headroom. It later uses
skb_is_nonlinear() to decide whether to set XDP_FLAGS_HAS_FRAGS and
xdp_frags_size.

That exposes frag_list data to XDP as if it were stored in frags[], but
frags[] is empty. AF_XDP copy mode can then trust the bogus XDP fragment
metadata, walk an empty fragment entry, and crash in memcpy() from
__xsk_rcv().

Route non-linear skbs through skb_pp_cow_data() before exposing them to
XDP, and only advertise XDP frags when the resulting skb has frags[].
skb_copy_bits() already handles frag_list input, and skb_pp_cow_data()
builds frags[] output with skb_add_rx_frag(), which is the
representation XDP multi-buffer expects.

## Which versions are affected by CVE-2026-74476?


## How do I fix CVE-2026-74476?

Apply the vendor's patch.

## Is CVE-2026-74476 being exploited?

There is no known exploitation of CVE-2026-74476 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74476 and fix it if it is affected.

What it is: CVE-2026-74476 is a critical vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74476 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-2026-74476/ (Markdown: https://insights.sbomify.com/CVE-2026-74476/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74476
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74476
- OSV: https://osv.dev/vulnerability/CVE-2026-74476

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74476/
Summaries are generated and may contain mistakes; the official description above is the record.