# CVE-2026-74612: veth: fix skb length accounting after XDP frag adjustment

> A Linux kernel veth driver flaw allows attackers to read kernel memory and cause crashes via crafted UDP packets with XDP adjustments.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/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:** 22 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-97053, BELL-CVE-2026-74612, DEBIAN-CVE-2026-74612, GHSA-pg5f-gw23-248r, SUSE-SU-2026:24021-1, SUSE-SU-2026:24039-1, SUSE-SU-2026:24057-1, SUSE-SU-2026:24073-1, SUSE-SU-2026:4434-1, SUSE-SU-2026:4538-1, UBUNTU-CVE-2026-74612

## What is CVE-2026-74612?

CVE-2026-74612 is a critical vulnerability in Linux, published on 22 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: fix skb length accounting after XDP frag adjustment

veth exposes non-linear skb fragments through an xdp_buff. If an XDP
program adjusts the fragment area, veth_xdp_rcv_skb() copies
xdp_frags_size back to skb->data_len but leaves skb->len containing the
old fragment contribution.

After a fragment shrink, this makes skb_headlen() larger than the actual
linear area. In the reproduced UDP receive path, __skb_datagram_iter()
copied 1024 bytes past the actual linear tail to userspace, starting at
struct skb_shared_info. The copied bytes included the affected skb's
nr_frags, xdp_frags_size, and a kernel pointer from
skb_shinfo(skb)->frags[0]. Real packet data was displaced by the same
amount and truncated at the end.

Subtract the old data_len before replacing it and add the new data_len
afterwards, keeping skb->len and skb->data_len synchronized.

Additionally, bpf_xdp_pull_data() can advance data_end while leaving
frags present. The skb is then still non-linear, so the old
__skb_put(skb, off) triggers SKB_LINEAR_ASSERT().

Use skb_set_tail_pointer() and update skb->len explicitly instead,
following bpf_prog_run_generic_xdp(). Unlike __skb_put(),
skb_set_tail_pointer() does not require a linear skb.

A 60000-byte UDP datagram on a veth pair with MTU 64000 was shortened by
1024 bytes from its fragment area. Before the fix, all 10 runs produced
corrupted payloads. After the fix, all 10 runs matched the expected
payload exactly. A forced-tailroom reproducer also exercises
bpf_xdp_pull_data() with frags still present; the old code triggers
SKB_LINEAR_ASSERT(), while this fix passes 10/10 runs.

## Which versions are affected by CVE-2026-74612?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kernel-livepatch-SLE15-SP7-RT_Update_20` | SUSE:Linux Enterprise Live Patching 15 SP7 | All versions | 2-150700.2.1 |
| `kernel-livepatch-SLE15-SP7_Update_21` | SUSE:Linux Enterprise Live Patching 15 SP7 | All versions | 2-150700.2.1 |
| `kernel-livepatch-MICRO-6-0-RT_Update_29` | SUSE:Linux Micro 6.0 | All versions | 2-1.1 |
| `kernel-livepatch-MICRO-6-0_Update_29` | SUSE:Linux Micro 6.0 | All versions | 2-1.1 |
| `kernel-livepatch-MICRO-6-0-RT_Update_29` | SUSE:Linux Micro 6.1 | All versions | 2-1.1 |
| `kernel-livepatch-MICRO-6-0_Update_29` | SUSE:Linux Micro 6.1 | All versions | 2-1.1 |

## How do I fix CVE-2026-74612?

Apply the vendor's patch.

## Is CVE-2026-74612 being exploited?

There is no known exploitation of CVE-2026-74612 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74612 and fix it if it is affected.

What it is: CVE-2026-74612 is a critical vulnerability in Linux, published on 22 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-2026-74612 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-2026-74612/ (Markdown: https://insights.sbomify.com/CVE-2026-74612/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74612
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74612
- OSV: https://osv.dev/vulnerability/CVE-2026-74612

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74612/
Summaries are generated and may contain mistakes; the official description above is the record.