CVE intelligence

CVE-2026-63917

Vulnerability intelligence

Published Jul 19, 2026Sources checked Oct 8, 2026

8.8HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-63917 and is rated High severity with a CVSS score of 8.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.2%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-63917?

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.

Source: NVD