Linux Kernel up to 6.12.77/6.18.19/6.19.8 nsfs may_see_all_namespaces permission

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 6.12.77/6.18.19/6.19.8. This issue affects the function may_see_all_namespaces of the component nsfs. This manipulation causes permission. This vulnerability is registered as CVE-2026-43403. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.12.77/6.18.19/6.19.8 and classified as critical. Affected by this vulnerability is the function may_see_all_namespaces of the component nsfs. The manipulation with an unknown input leads to a permission vulnerability. The CWE definition for the vulnerability is CWE-275. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: nsfs: tighten permission checks for ns iteration ioctls 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.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-43403 since 05/01/2026. The exploitation appears to be easy. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/22/2026). MITRE ATT&CK project uses the attack technique T1222 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 313431 (Linux Distros Unpatched Vulnerability : CVE-2026-43403), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.12.78, 6.18.20 or 6.19.9 eliminates this vulnerability. Applying the patch 3376b345df155ca36d8611857b41ff7d5183fc38/2f3dea284c761c890d676f77d5e55c0c496b4ef4/0ad650e60150eda789deca5e78a6a09d26bf8fc9/e6b899f08066e744f89df16ceb782e06868bd148 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (313431). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
• 6.12.20
• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.12.25
• 6.12.26
• 6.12.27
• 6.12.28
• 6.12.29
• 6.12.30
• 6.12.31
• 6.12.32
• 6.12.33
• 6.12.34
• 6.12.35
• 6.12.36
• 6.12.37
• 6.12.38
• 6.12.39
• 6.12.40
• 6.12.41
• 6.12.42
• 6.12.43
• 6.12.44
• 6.12.45
• 6.12.46
• 6.12.47
• 6.12.48
• 6.12.49
• 6.12.50
• 6.12.51
• 6.12.52
• 6.12.53
• 6.12.54
• 6.12.55
• 6.12.56
• 6.12.57
• 6.12.58
• 6.12.59
• 6.12.60
• 6.12.61
• 6.12.62
• 6.12.63
• 6.12.64
• 6.12.65
• 6.12.66
• 6.12.67
• 6.12.68
• 6.12.69
• 6.12.70
• 6.12.71
• 6.12.72
• 6.12.73
• 6.12.74
• 6.12.75
• 6.12.76
• 6.12.77
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 6.19.7
• 6.19.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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Entryinfo

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