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  4. CVE 2026 53341 fhandle fix uaf due to unlocked mntns read in
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Back to active CVEs
High · CVSS 7.8CVE-2026-53341

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

Answer in brief

CVE-2026-53341 records a High severity (CVSS 7.8) vulnerability in fhandle: fix UAF due to unlocked ->mnt_ns read in may_decode_fh(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jul 1, 2026Updated Oct 19, 2026Source checked Nov 4, 2026First seen by HOL Jul 1, 2026Material review Oct 19, 2026
Upstream Advisory

Key facts

Risk
High · CVSS 7.8
Exploitation
Not marked as known exploited
Affected software
9 mapped packages or products
Fix availability
Available

Why this deserves its current priority

CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
ProductAffected versionsFixed versions
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:*Not reportedNot reported
Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Linux/Linuxgeneric>=620c266f394932e5decc4b34683a75dfc59dc2f4 <15ea8dc42a02259d49dee38a658d40f60fcd75ed || >=620c266f394932e5decc4b34683a75dfc59dc2f4 <32138633e51e6db59e474765cf93268c92b42888 || >=620c266f394932e5decc4b34683a75dfc59dc2f4 <a8ed2c29fcfdac78db96c9da4e659c8a513f2a94 || >=620c266f394932e5decc4b34683a75dfc59dc2f4 <40ab6644b99685755f740b872c00ef40d9aa870e15ea8dc42a02259d49dee38a658d40f60fcd75ed, 32138633e51e6db59e474765cf93268c92b42888, a8ed2c29fcfdac78db96c9da4e659c8a513f2a94, 40ab6644b99685755f740b872c00ef40d9aa870e
Linux/Linuxgeneric6.11Not reported

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
  2. 2Review the reported fix. Update Linux/Linux to 15ea8dc42a02259d49dee38a658d40f60fcd75ed if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Jul 1, 2026

    Evidence: source:cvelist:source_dates:source-dates:record
  2. Source modified

    Oct 19, 2026

    Evidence: source:cvelist:source_dates:source-dates:record
  3. First seen by HOL

    Jul 1, 2026

Sources and claim methodology

  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

Record context

Vulnerability class
Memory Corruption
EPSS
Not reported
CWE IDs
CWE-416
Source
CVE List V5
Source checked
Nov 4, 2026
References
4 linked sources
Open source record