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CVE-2026-52906

7.7 · HIGH

In the Linux kernel, the following vulnerability has been resolved: 9p: fix access mode flags being ORed instead of replaced Since commit 1f3e4142c0eb ("9p: convert to the new mount API"), v9fs_a…

Published Jun 9, 2026EPSS 0.18%

Overview

CVE-2026-52906 is a high-severity vulnerability. It was published on June 9, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

9p: fix access mode flags being ORed instead of replaced

Since commit 1f3e4142c0eb ("9p: convert to the new mount API"),

v9fs_apply_options() applies parsed mount flags with |= onto flags

already set by v9fs_session_init(). For 9P2000.L, session_init sets

V9FS_ACCESS_CLIENT as the default, so when the user mounts with

"access=user", both bits end up set. Access mode checks compare

against exact values, so having both bits set matches neither mode.

This causes v9fs_fid_lookup() to fall through to the default switch

case, using INVALID_UID (nobody/65534) instead of current_fsuid()

for all fid lookups. Root is then unable to chown or perform other

privileged operations.

Fix by clearing the access mask before applying the user's choice.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/b8f037e87a083291190204b959cda417aaf01058Refgit.kernel.org/stable/c/da2346a48a5a1fed86c3fe3d73c0b60e7b3027c9

How CyberStrike helps

Frequently asked questions

What is CVE-2026-52906?

CVE-2026-52906 is a high-severity vulnerability. It was published on June 9, 2026 and has a CVSS 3.1 base score of 7.7 (HIGH).

How severe is CVE-2026-52906?

This vulnerability has a CVSS 3.1 base score of 7.7, rated HIGH. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-52906?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-52906?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-52906 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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