CVE-2026-52909: Linux kernel · ip6_vti: set netns_immutable on the fallback device.
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.8 High · fixed in f4b6b4af7ef0661ac153c6f7eb1030aa8482c1a3 : patch Linux kernel soon.
Data as of 26 Oct 2026, 09:29 UTC
- 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 f4b6b4af7ef0661ac153c6f7eb1030aa8482c1a3, ecf8904067dcba0dad86ece80874841e60317885, dcdce3bc9f08026ff3739ee7339e1bef526fc5f3 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jun 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: set netns_immutable on the fallback device. john1988 and Noam Rathaus reported that vti6_init_net() does not set the netns_immutable flag on the per-netns fallback tunnel device (ip6_vti0). Other similar tunnel drivers (like ip6_tunnel, sit, ip6_gre, and ip_tunnel) correctly set this flag during their fallback device initialization to prevent them from being moved to another network namespace.
References
- git.kernel.org/stable/c/12acc977838c943636fb01e2f3087d2e4cc3b7cc (opens in a new tab)
- git.kernel.org/stable/c/7f28e3948c59481f8db9c9638e204258d26b4e41 (opens in a new tab)
- git.kernel.org/stable/c/12c65e2c7fef507551bd7b52123598a761662c01 (opens in a new tab)
- git.kernel.org/stable/c/f4b6b4af7ef0661ac153c6f7eb1030aa8482c1a3 (opens in a new tab)
- git.kernel.org/stable/c/c5dbd669db5a426b3025512322e1bf2cdbe14305 (opens in a new tab)
- git.kernel.org/stable/c/ecf8904067dcba0dad86ece80874841e60317885 (opens in a new tab)
- git.kernel.org/stable/c/dcdce3bc9f08026ff3739ee7339e1bef526fc5f3 (opens in a new tab)
- git.kernel.org/stable/c/d289d5307762d1838aaece22c6b6fcad9e8865f9 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)