Use After Free Affecting kernel-azure-extra package, versions <6.12.0-160000.38.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-SLES1600-KERNELAZUREEXTRA-20310601
- published30 Sept 2026
- disclosed22 Sept 2026
Introduced: 22 Sep 2026
NewCVE-2026-53341 (opens in a new tab)How to fix?
Upgrade SLES:16.0.0 kernel-azure-extra to version 6.12.0-160000.38.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-azure-extra package and not the kernel-azure-extra package as distributed by SLES.
See How to fix? for SLES:16.0.0 relevant fixed versions and status.
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
- https://www.suse.com/security/cve/CVE-2026-53341.html
- https://bugzilla.suse.com/1270139
- https://git.kernel.org/stable/c/15ea8dc42a02259d49dee38a658d40f60fcd75ed
- https://git.kernel.org/stable/c/32138633e51e6db59e474765cf93268c92b42888
- https://git.kernel.org/stable/c/40ab6644b99685755f740b872c00ef40d9aa870e
- https://git.kernel.org/stable/c/a8ed2c29fcfdac78db96c9da4e659c8a513f2a94