{"id":"CVE-2026-53341","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nfhandle: fix UAF due to unlocked ->mnt_ns read in may_decode_fh()\n\nmay_decode_fh() accesses mount::mnt_ns without holding any locks; that\nmeans the mount can concurrent…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nfhandle: fix UAF due to unlocked ->mnt_ns read in may_decode_fh()\n\nmay_decode_fh() accesses mount::mnt_ns without holding any locks; that\nmeans the mount can concurrent…","severity":"none","published":"2026-07-01","updated":"2026-07-04","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-53341","references":[{"url":"https://git.kernel.org/stable/c/15ea8dc42a02259d49dee38a658d40f60fcd75ed","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/32138633e51e6db59e474765cf93268c92b42888","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/40ab6644b99685755f740b872c00ef40d9aa870e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a8ed2c29fcfdac78db96c9da4e659c8a513f2a94","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00126,"epssPercentile":0.02675,"ingestedAt":"2026-07-04T13:56:12.017Z","slug":"CVE-2026-53341","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nfhandle: fix UAF due to unlocked ->mnt_ns read in may_decode_fh()\n\nmay_decode_fh() accesses mount::mnt_ns without holding any locks; that\nmeans the mount can concurrently be unmounted, and the mnt_namespace can\nconcurrently be freed after an RCU grace period.\n\nThis race can happens as follows, assuming that the mount point was\ncreated by open_tree(..., OPEN_TREE_CLONE):\n\nthread 1            thread 2            RCU\n                    __do_sys_open_by_handle_at\n                      do_handle_open\n                        handle_to_path\n                          may_decode_fh\n                            is_mounted\n                              [mount::mnt_ns access]\n                            [mount::mnt_ns access]\n__do_sys_close\n  fput_close_sync\n    __fput\n      dissolve_on_fput\n        umount_tree\n        class_namespace_excl_destructor\n          namespace_unlock\n            free_mnt_ns\n              mnt_ns_tree_remove\n                call_rcu(mnt_ns_release_rcu)\n                                        mnt_ns_release_rcu\n                                          mnt_ns_release\n                                            kfree\n                            [mnt_namespace::user_ns access] **UAF**\n\nFix it by taking rcu_read_lock() around the mount::mnt_ns access, like\nin __prepend_path().\nAdditionally, document the semantics of mount::mnt_ns, and use WRITE_ONCE()\nfor writers that can race with lockless readers.\n\nThis bug is unreachable unless one of the following is set:\n\n - CONFIG_PREEMPTION\n - CONFIG_RCU_STRICT_GRACE_PERIOD\n\nbecause it requires an RCU grace period to happen during a syscall without\nan explicit preemption.\n\nThis doesn't seem to have interesting security impact; worst-case, it could\nleak the result of an integer comparison to userspace (from the level\ncheck in cap_capable()), cause an endless loop, or crash the kernel by\ndereferencing an invalid address.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}