fhandle: fix UAF due to unlocked ->mnt_ns read in may_decode_fh()
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 dereferen
CVE-2026-53341
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-53341
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "620c266f394932e5decc4b34683a75dfc59dc2f4",
"lessThan": "15ea8dc42a02259d49dee38a658d40f60fcd75ed",
"versionType": "git"
},
{
"status": "affected",
"version": "620c266f394932e5decc4b34683a75dfc59dc2f4",
"lessThan": "32138633e51e6db59e474765cf93268c92b42888",
"versionType": "git"
},
{
"status": "affected",
"version": "620c266f394932e5decc4b34683a75dfc59dc2f4",
"lessThan": "a8ed2c29fcfdac78db96c9da4e659c8a513f2a94",
"versionType": "git"
},
{
"status": "affected",
"version": "620c266f394932e5decc4b34683a75dfc59dc2f4",
"lessThan": "40ab6644b99685755f740b872c00ef40d9aa870e",
"versionType": "git"
}
],
"programFiles": [
"fs/fhandle.c",
"fs/mount.h",
"fs/namespace.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.11"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.11",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.95",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.36",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.13",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/fhandle.c",
"fs/mount.h",
"fs/namespace.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-53341
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #40805 · Revision 1
- Added to Heist Feed
- Publisher date