CVE-2026-43391: nsfs: tighten permission checks for handle opening

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-08 · updated 2026-09-07

Description

In the Linux kernel, the following vulnerability has been resolved: nsfs: tighten permission checks for handle opening Even privileged services should not necessarily be able to see other privileged service's namespaces so they can't leak information to each other. Use may_see_all_namespaces() helper that centralizes this policy until the nstree adapts.

Affected products

Linux kernel: from 6.18 before 6.19.9; 7.0-rc1, 7.0-rc2 — fixed in 6.19.9

How to fix

Upgrade to a fixed version: Linux kernel 6.19.9. Check the vendor advisory for mitigations.

References

https://git.kernel.org/stable/c/1797ee11451f1b2be69863a9f5bd43b948813fdf
https://git.kernel.org/stable/c/24ebaf6676ae4f74f4856eb645959b15e62bc1b4
https://git.kernel.org/stable/c/d2324a9317f00013facb0ba00b00440e19d2af5e

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