CVE-2026-52906

Unauthorized 9P access via merged mode flags

Published Jun 9, 2026 · Updated Jun 9, 2026

Authorization bypass in Linux Kernel 6.19 allows local users to read and write restricted 9P shares through local file operations. v9fs_apply_options() ORs a parsed access choice into the default V9FS_ACCESS_CLIENT flag instead of replacing the access-mode bits, so v9fs_fid_lookup() uses a shared INVALID_UID attachment. A local user needs filesystem access to an already mounted 9P2000.L share using access=user or a numeric UID; mounting such a share requires CAP_SYS_ADMIN.

CVSS severity7.7
High
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Linux Kernel 6.19 allows local users to read and write restricted 9P shares through local file operations. v9fs_apply_options() ORs a parsed access choice into the default V9FS_ACCESS_CLIENT flag instead of replacing the access-mode bits, so v9fs_fid_lookup() uses a shared INVALID_UID attachment. A local user needs filesystem access to an already mounted 9P2000.L share using access=user or a numeric UID; mounting such a share requires CAP_SYS_ADMIN.

The record

CVE
CVE-2026-52906
Published
Jun 9, 2026
Updated
Jun 9, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1005, T1565
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 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=1f3e4142c0eb178089ea0cbc97506a061470ad27 <b8f037e87a083291190204b959cda417aaf01058
  2. Affected versionversion=1f3e4142c0eb178089ea0cbc97506a061470ad27 <da2346a48a5a1fed86c3fe3d73c0b60e7b3027c9
  3. Affected versionversion=6.19

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1f3e4142c0eb178089ea0cbc97506a061470ad27 <b8f037e87a083291190204b959cda417aaf01058; version=1f3e4142c0eb178089ea0cbc97506a061470ad27 <da2346a48a5a1fed86c3fe3d73c0b60e7b3027c9; version=6.19

Published CVSS scores

7.7LinuxCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1005Data from Local System
T1565Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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