CVE-2026-52906 (GCVE-0-2026-52906)

Vulnerability from cvelistv5 – Published: 2026-06-09 12:36 – Updated: 2026-06-14 18:09
VLAI
Title
9p: fix access mode flags being ORed instead of replaced
Summary
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.
Severity
7.7 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1f3e4142c0eb178089ea0cbc97506a061470ad27 , < b8f037e87a083291190204b959cda417aaf01058 (git)
Affected: 1f3e4142c0eb178089ea0cbc97506a061470ad27 , < da2346a48a5a1fed86c3fe3d73c0b60e7b3027c9 (git)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 7.0.4 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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    "dateReserved": "2026-06-09T07:44:35.366Z",
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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-28T07:43:34+00:00",
      "cve": "CVE-2026-52906",
      "id": "CVE-2026-52906",
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      "source": "Red Hat CSAF VEX",
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      "title": "kernel: 9p: fix access mode flags being ORed instead of replaced",
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      "cve": "CVE-2026-52906",
      "id": "CVE-2026-52906",
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      "status": "interim",
      "title": "SUSE CVE CVE-2026-52906",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-52906.json",
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    }
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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