udp: fix potential use-after-free in tunnel segmentation

Summary

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head, the saved UDP header pointer is no longer valid.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.

Timeline

1. Aug 22, 2026, 3:33 PM UTCCVE published
2. Oct 16, 2026, 7:15 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: total

3. Oct 16, 2026, 7:16 PM UTCRecord last updated

Affected versions

• Linux Linux

  From dbef491ebe7f3a4fb1b9111878b86a426fd540b7 · fixed in 6a733a38b983d8c2e222f13968209010cf44de87; From dbef491ebe7f3a4fb1b9111878b86a426fd540b7 · fixed in 19d89b13a43640b2da2f277ee462d919d988cb6f; From dbef491ebe7f3a4fb1b9111878b86a426fd540b7 · fixed in b3df61bb745eb5201eac22679a2839d4ccbf3442; From dbef491ebe7f3a4fb1b9111878b86a426fd540b7 · fixed in 1ae134c012e10384cdac420b5cc6e0615cde0b55; From dbef491ebe7f3a4fb1b9111878b86a426fd540b7 · fixed in 5161e67c561c4f28a5d9335a6e859b02511de92b; From dbef491ebe7f3a4fb1b9111878b86a426fd540b7 · fixed in 64d322c288577793eedd352b96ef75234ed380fe; From dbef491ebe7f3a4fb1b9111878b86a426fd540b7 · fixed in 588d4a6795d99d080f74ef0b5f391ea8c453ae5d; From dbef491ebe7f3a4fb1b9111878b86a426fd540b7 · fixed in d0f86fb36eb260abd10007b62c9dcc1028e03e61

• Linux Linux

  4.6

• KernelLinux

  From 4.6.0 · fixed in 5.10.265; From 5.11.0 · fixed in 5.15.216; From 5.16.0 · fixed in 6.1.183; From 6.2.0 · fixed in 6.6.152; From 6.7.0 · fixed in 6.12.104; From 6.13.0 · fixed in 6.18.45; From 6.19.0 · fixed in 7.1.9

References 8