CVE-2026-43403

Cross-service namespace disclosure via missing policy check

Published May 8, 2026 · Updated May 8, 2026

Improper access control in Linux Kernel nsfs allows local users to inspect other services’ namespaces through namespace-iteration ioctls. The NS_MNT_GET_NEXT and NS_MNT_GET_PREV handlers accept CAP_SYS_ADMIN in the target mount namespace’s owning user namespace without applying may_see_all_namespaces(). Exploitation requires local access and that namespace capability; the bounded consequence is cross-service namespace information disclosure.

CVSS severity8.8
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Linux Kernel nsfs allows local users to inspect other services’ namespaces through namespace-iteration ioctls. The NS_MNT_GET_NEXT and NS_MNT_GET_PREV handlers accept CAP_SYS_ADMIN in the target mount namespace’s owning user namespace without applying may_see_all_namespaces(). Exploitation requires local access and that namespace capability; the bounded consequence is cross-service namespace information disclosure.

The record

CVE
CVE-2026-43403
Published
May 8, 2026
Updated
May 8, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1613
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.12
  2. Affected versionversion=a1d220d9dafa8d76ba60a784a1016c3134e6a1e8 <0ad650e60150eda789deca5e78a6a09d26bf8fc9
  3. Affected versionversion=a1d220d9dafa8d76ba60a784a1016c3134e6a1e8 <2f3dea284c761c890d676f77d5e55c0c496b4ef4
  4. Affected versionversion=a1d220d9dafa8d76ba60a784a1016c3134e6a1e8 <3376b345df155ca36d8611857b41ff7d5183fc38
  5. Affected versionversion=a1d220d9dafa8d76ba60a784a1016c3134e6a1e8 <e6b899f08066e744f89df16ceb782e06868bd148

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.12; version=a1d220d9dafa8d76ba60a784a1016c3134e6a1e8 <0ad650e60150eda789deca5e78a6a09d26bf8fc9; version=a1d220d9dafa8d76ba60a784a1016c3134e6a1e8 <2f3dea284c761c890d676f77d5e55c0c496b4ef4; version=a1d220d9dafa8d76ba60a784a1016c3134e6a1e8 <3376b345df155ca36d8611857b41ff7d5183fc38; version=a1d220d9dafa8d76ba60a784a1016c3134e6a1e8 <e6b899f08066e744f89df16ceb782e06868bd148

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1613Container and Resource Discovery

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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