CVE-2026-74705: udp: fix potential use-after-free in tunnel segmentation

Severity: critical (CVSS 10.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-22 · updated 2026-10-16

Description

In the Linux kernel, the following vulnerability has been resolved: udp: fix potential use-after-free in tunnel segmentation __skb_udp_tunnel_segment() gets the UDP header before ensuring the tunnel header is in the skb head. If the pull reallocates skb->head, the saved UDP header pointer is no longer valid. Get the UDP header after the pull to avoid a potential use-after-free.

Affected products

Linux kernel: 4.6 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux kernel 7.2. Check the vendor advisory for mitigations.

References

https://git.kernel.org/stable/c/19d89b13a43640b2da2f277ee462d919d988cb6f
https://git.kernel.org/stable/c/1ae134c012e10384cdac420b5cc6e0615cde0b55
https://git.kernel.org/stable/c/5161e67c561c4f28a5d9335a6e859b02511de92b
https://git.kernel.org/stable/c/588d4a6795d99d080f74ef0b5f391ea8c453ae5d
https://git.kernel.org/stable/c/64d322c288577793eedd352b96ef75234ed380fe
https://git.kernel.org/stable/c/6a733a38b983d8c2e222f13968209010cf44de87
https://git.kernel.org/stable/c/b3df61bb745eb5201eac22679a2839d4ccbf3442
https://git.kernel.org/stable/c/d0f86fb36eb260abd10007b62c9dcc1028e03e61

Get alerted when CVE-2026-74705 or the next vulnerability affects your stack