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CVE-2026-23268 Linux CVE debrief

A confused-deputy vulnerability in the Linux kernel's AppArmor security module allows an unprivileged local user to perform privileged policy management operations. The apparmorfs interfaces for loading, replacing, and removing security profiles were accessible with permissions that permitted file descriptor passing attacks. An unprivileged attacker could open these interfaces and pass the resulting file descriptor to a privileged process, manipulating that process into performing policy writes on their behalf. Successful exploitation enables complete AppArmor policy management, including removing confinement from processes, causing denial of service by denying all execution, bypassing unprivileged user namespace restrictions, and potentially exploiting kernel bugs for local privilege escalation. The fix ensures that the task writing to the interface holds privileges that are a subset of the task that originally opened the interface, closing the delegation bypass for unconfined processes.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-03-18
Original CVE updated
2026-05-29
Advisory published
2026-03-18
Advisory updated
2026-05-29

Who should care

Linux system administrators, kernel maintainers, security teams operating containerized or multi-tenant environments relying on AppArmor for mandatory access control, and organizations with compliance requirements for process confinement.

Technical summary

The vulnerability exists in the apparmorfs policy management interfaces, which are exposed with permissions that allow non-root processes to load policy to different namespaces. The permission model (0666) cannot be simply restricted to 0600 because legitimate use cases require non-root namespace policy loading. The attack vector involves an unprivileged local user opening the apparmorfs interface to obtain a file descriptor, then using a confused deputy attack to pass that descriptor to a privileged process and induce writes. The fix implements a privilege subset check at write time: the writing task's privileges must be a subset of the opening task's privileges. This check already existed for confined processes via policy enforcement, but unconfined processes could previously delegate access through file descriptor passing, bypassing the policy check. The patch closes this gap by enforcing the subset check for all tasks, including unconfined ones.

Defensive priority

high

Recommended defensive actions

  • Apply the relevant stable kernel patch for your kernel series: 5.10.253+, 5.15.203+, 6.1.169+, 6.6.130+, 6.12.77+, 6.18.18+, 6.19.8+, or 7.0-rc4+
  • Upgrade to a patched kernel version as listed in the CPE version ranges
  • If immediate patching is not possible, restrict access to processes that may be manipulated into writing to file descriptors on behalf of unprivileged users
  • Monitor for anomalous AppArmor policy changes in environments running affected kernel versions
  • Review and audit processes running with elevated privileges that accept file descriptors from untrusted sources

Evidence notes

CVE published 2026-03-18; modified 2026-05-29. Multiple stable kernel patches released. Affected versions span Linux kernel 4.11 through 6.19.8, plus 7.0-rc1 through rc3. Third-party advisory from Qualys published 2026-03-10. CVSS 3.1 vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-23268 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-23268

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-23268 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-23268

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/0fc63dd9170643d15c25681fca792539e23f4640

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/17debf5586020790b5717f96e5e6a3ca5bb961ab

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/33ee909702e047c94aaf41d4eea35626d509802c

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/4cafce4d6d0a66ec27e3af5637c11901d60189fa

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/6601e13e82841879406bf9f369032656f441a425

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/a407a078cd41b5261b99d822af784bd9f136eb4d

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/b60b3f7a35c46b2e0ca934f9c988b8fca06d76c6

    416baaa9-dc9f-4396-8d5f-8c081fb06d67 - Patch

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.