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VulnerabilityPublished Updated

CVE-2026-53341: Linux kernel · Use After Free

Affects Linux kernelSource CVE Database V5

0

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

Data as of 26 Oct 2026, 15:59 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.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

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–

Description

In the Linux kernel, the following vulnerability has been resolved: fhandle: fix UAF due to unlocked ->mnt_ns read in may_decode_fh() may_decode_fh() accesses mount::mnt_ns without holding any locks; that means the mount can concurrently be unmounted, and the mnt_namespace can concurrently be freed after an RCU grace period. This race can happens as follows, assuming that the mount point was created by open_tree(..., OPEN_TREE_CLONE): thread 1 thread 2 RCU __do_sys_open_by_handle_at do_handle_open handle_to_path may_decode_fh is_mounted [mount::mnt_ns access] [mount::mnt_ns access] __do_sys_close fput_close_sync __fput dissolve_on_fput umount_tree class_namespace_excl_destructor namespace_unlock free_mnt_ns mnt_ns_tree_remove call_rcu(mnt_ns_release_rcu) mnt_ns_release_rcu mnt_ns_release kfree [mnt_namespace::user_ns access] **UAF** Fix it by taking rcu_read_lock() around the mount::mnt_ns access, like in __prepend_path(). Additionally, document the semantics of mount::mnt_ns, and use WRITE_ONCE() for writers that can race with lockless readers. This bug is unreachable unless one of the following is set: - CONFIG_PREEMPTION - CONFIG_RCU_STRICT_GRACE_PERIOD because it requires an RCU grace period to happen during a syscall without an explicit preemption. This doesn't seem to have interesting security impact; worst-case, it could leak the result of an integer comparison to userspace (from the level check in cap_capable()), cause an endless loop, or crash the kernel by dereferencing an invalid address.

References

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