PT-2026-61234 · Linux · Linux

CVE-2026-63917 · Published 2026-07-19 · Updated 2026-07-19

NVD

CVSS v3.1

8.8

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

In the Linux kernel, the following vulnerability has been resolved:

ip6: vti: Use ip6 tnl.net in vti6 changelink().

ip netns add ns1 ip netns add ns2 ip -n ns1 link add vti6 test type vti6 remote ::1 local ::2 key 7 ip -n ns1 link set vti6 test netns ns2 ip -n ns2 link set vti6 test type vti6 remote ::3 local ::4 key 9 ip netns del ns2 ip netns del ns1 [ 132.495484] ------------[ cut here ]------------ [ 132.497609] kernel BUG at net/core/dev.c:12376!

Commit 61220ab34948 ("vti6: Enable namespace changing") dropped NETIF F NETNS LOCAL from vti6 devices. A vti6 tunnel can then move through IFLA NET NS FD. After the move dev net(dev) points at the new netns while t->net stays at the creation netns.

vti6 changelink() and vti6 update() still use dev net(dev) and dev net(t->dev). They unlink from one per netns hash and relink into another. The creation netns is left with a stale entry. cleanup net() of that netns later walks freed memory.

Reachable from an unprivileged user namespace (unshare --user --map-root-user --net). Cross tenant scope on container hosts.

Fix

Related Identifiers

CVE-2026-63917

Affected Products

Linux

References · 9

• https://nvd.nist.gov/vuln/detail/CVE-2026-63917 · Security Note
• https://git.kernel.org/stable/c/11b326fb0a374f4654f9be22d0f0f7abd9f7d3fe · Note
• https://git.kernel.org/stable/c/d9c5eecdb3c740e65038651db7c686b10d76d1bc · Note
• https://git.kernel.org/stable/c/f5c68875e25f331e497ddfbe81e2d8163a87f136 · Note
• https://git.kernel.org/stable/c/fc32be9ac2788524c6b24efd681cce7a6e731a92 · Note
• https://git.kernel.org/stable/c/225b467e3b631f38be22e4b38062a1fed02fdd21 · Note
• https://git.kernel.org/stable/c/0cdce7618464f7fb06f461e8f4ad575cb1d570f4 · Note
• https://git.kernel.org/stable/c/f1e89a943ee574d0f2f16246eb3f2d7330fdeb03 · Note
• https://git.kernel.org/stable/c/ee1778ba0f5cb53be771f97017d01eb356c797bf · Note