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VulnerabilityPublished Updated

CVE-2026-53341: Linux kernel · fhandle: fix UAF due to unlocked ->mnt_ns read in may_decode_fh()

Source GCVE Database

0
Authoritative record:CVE-2026-53341· High 7.8

Not known to be exploited · CVSS 7.8 High · fixed in a8ed2c29fcfdac78db96c9da4e659c8a513f2a94 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in a8ed2c29fcfdac78db96c9da4e659c8a513f2a94, 32138633e51e6db59e474765cf93268c92b42888, 40ab6644b99685755f740b872c00ef40d9aa870e +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Linux kernel to a8ed2c29fcfdac78db96c9da4e659c8a513f2a94, 32138633e51e6db59e474765cf93268c92b42888, 40ab6644b99685755f740b872c00ef40d9aa870e or 15ea8dc42a02259d49dee38a658d40f60fcd75ed.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 620c266f394932e5decc4b34683a75dfc59dc2f4, < a8ed2c29fcfdac78db96c9da4e659c8a513f2a94
Fixed in
  • a8ed2c29fcfdac78db96c9da4e659c8a513f2a94
LinuxLinuxAffected
  • ≥ 620c266f394932e5decc4b34683a75dfc59dc2f4, < 32138633e51e6db59e474765cf93268c92b42888
Fixed in
  • 32138633e51e6db59e474765cf93268c92b42888
LinuxLinuxAffected
  • ≥ 620c266f394932e5decc4b34683a75dfc59dc2f4, < 40ab6644b99685755f740b872c00ef40d9aa870e
Fixed in
  • 40ab6644b99685755f740b872c00ef40d9aa870e
LinuxLinuxAffected
  • ≥ 620c266f394932e5decc4b34683a75dfc59dc2f4, < 15ea8dc42a02259d49dee38a658d40f60fcd75ed
Fixed in
  • 15ea8dc42a02259d49dee38a658d40f60fcd75ed
LinuxLinuxAffected
  • =6.11
Fixed in–

AI-suggested

A fix is available that adds proper RCU locking around the mount::mnt_ns access in may_decode_fh() and uses WRITE_ONCE() for writers to prevent races. Users should apply the official kernel updates that include this fix. Since this is a kernel vulnerability, updating to a patched kernel version is the recommended mitigation. Patch status is not explicitly confirmed in the provided data; check the vendor advisory for current remediation guidance.

Description

A use-after-free (UAF) vulnerability in the Linux kernel's may_decode_fh() function was resolved. The issue arises because may_decode_fh() accesses mount::mnt_ns without proper locking, allowing a race condition where the mount namespace can be freed concurrently. This race requires specific kernel configurations (CONFIG_PREEMPTION or CONFIG_RCU_STRICT_GRACE_PERIOD) and an RCU grace period during a syscall. The vulnerability could lead to leaking an integer comparison result, cause an endless loop, or crash the kernel by dereferencing invalid memory.

References

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