CVE-2026-63917: Linux kernel · ip6: vti: Use ip6_tnl.net in vti6_changelink().
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 8.8 High · fixed in fc32be9ac2788524c6b24efd681cce7a6e731a92 : patch Linux kernel soon.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in fc32be9ac2788524c6b24efd681cce7a6e731a92, f5c68875e25f331e497ddfbe81e2d8163a87f136, f1e89a943ee574d0f2f16246eb3f2d7330fdeb03 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
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.
References
- git.kernel.org/stable/c/0cdce7618464f7fb06f461e8f4ad575cb1d570f4 (opens in a new tab)
- git.kernel.org/stable/c/f5c68875e25f331e497ddfbe81e2d8163a87f136 (opens in a new tab)
- git.kernel.org/stable/c/d9c5eecdb3c740e65038651db7c686b10d76d1bc (opens in a new tab)
- git.kernel.org/stable/c/f1e89a943ee574d0f2f16246eb3f2d7330fdeb03 (opens in a new tab)
- git.kernel.org/stable/c/225b467e3b631f38be22e4b38062a1fed02fdd21 (opens in a new tab)
- git.kernel.org/stable/c/fc32be9ac2788524c6b24efd681cce7a6e731a92 (opens in a new tab)
- git.kernel.org/stable/c/ee1778ba0f5cb53be771f97017d01eb356c797bf (opens in a new tab)
- git.kernel.org/stable/c/11b326fb0a374f4654f9be22d0f0f7abd9f7d3fe (opens in a new tab)