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Advisory severityHigh7.0Red Hat Linux

High [CVE-2026-63917] Use ip6_tnl.net in vti6_changelink

This high-severity Red Hat Linux advisory covers CVE-2026-63917 affecting Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support, Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-63917 Source published Source updated

VulniPulse record published Record updated

CVE-2026-63917
Affected products & platforms
Red Hat LinuxLinux Kernel
Open source advisory

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Summary

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. A flaw was found in the Linux kernel's IPv6 Virtual Tunnel Interface (vti6) component.

An unprivileged local user, particularly within a user namespace, could exploit a vulnerability related to incorrect network namespace handling during the movement of a vti6 tunnel.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · high-confidence parse· fetched 7 days ago·verify at source

Fixed versions
  • kernel-0:6.12.0-211.55.1.el10_2
  • kernel-0:6.12.0-55.108.1.el10_0
  • kernel-rt-0:4.18.0-553.164.1.rt7.505.el8_10
  • kernel-0:4.18.0-553.164.1.el8_10
  • kernel-0:4.18.0-305.211.1.el8_4
  • kernel-0:4.18.0-372.220.1.el8_6
  • kernel-0:4.18.0-477.172.1.el8_8
  • kernel-0:5.14.0-687.49.1.el9_8
  • kernel-0:5.14.0-284.197.1.el9_2
  • kernel-rt-0:5.14.0-284.197.1.rt14.482.el9_2
  • kernel-0:5.14.0-427.154.1.el9_4
  • kernel-0:5.14.0-570.146.1.el9_6
  • RHSA-2026:67471
  • RHSA-2026:75560
  • RHSA-2026:68532
  • RHSA-2026:68531
  • RHSA-2026:77217
  • RHSA-2026:77216
  • RHSA-2026:77301
  • RHSA-2026:68570
  • RHSA-2026:80908
  • RHSA-2026:82860
  • RHSA-2026:77218
  • RHSA-2026:74174

Official advisory · high-confidence parse· fetched 7 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • To mitigate this issue, prevent module ip6_vti from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.

Official advisory · high-confidence parse· fetched 7 days ago·verify at source

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