{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-38306","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T04:51:24.002Z","datePublished":"2025-07-10T07:42:16.806Z","dateUpdated":"2026-08-05T12:01:05.449Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:01:05.449Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs/fhandle.c: fix a race in call of has_locked_children()\n\nmay_decode_fh() is calling has_locked_children() while holding no locks.\nThat's an oopsable race...\n\nThe rest of the callers are safe since they are holding namespace_sem and\nare guaranteed a positive refcount on the mount in question.\n\nRename the current has_locked_children() to __has_locked_children(), make\nit static and switch the fs/namespace.c users to it.\n\nMake has_locked_children() a wrapper for __has_locked_children(), calling\nthe latter under read_seqlock_excl(&mount_lock)."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerability is reached through local syscalls — `open_by_handle_at(2)` drives the unlocked `has_locked_children()` traversal while `mount(2)`/`umount(2)` mutate the `mnt_mounts` list. No network or physical access is involved.\nAC:L - The attacker controls both sides of the race entirely, spinning one thread on `open_by_handle_at(..., O_DIRECTORY)` and another on bind-mount/umount in their own mount namespace; the check runs before the file handle is even copied in or validated, so the window can be hammered without needing a valid handle or any condition outside attacker control.\nPR:L - An unprivileged local user reaches the vulnerable call by running `unshare -Urm`, since the gate only needs `CAP_SYS_ADMIN` over the mount namespace's owning user namespace — which is the attacker's own newly created user namespace. It is likewise reachable by any process that is root inside an ordinary container.\nUI:N - The attacker triggers everything from their own threads; no victim action, mount, or file access by another user is required.\nS:U - The corrupted state and the resulting impact are both within the kernel's own security authority, with no crossing of a VM, hypervisor, or IOMMU boundary.\nC:H - Traversing the concurrently modified list reads freed `struct mount` memory and feeds a stale `mnt_mountpoint` into `is_subdir()`/`d_ancestor()`, chasing attacker-groomable pointers; additionally, a raced result defeats the locked-mount gate, granting `HANDLE_CHECK_SUBTREE` and letting the attacker open directory handles into subtrees deliberately hidden by locked mounts.\nI:H - The use-after-free is on `mnt_cache` objects the attacker can spray at will via `mount()`, the standard basis for heap-corruption and control-flow primitives; the same bypass also yields a writable directory fd anchor beneath mounts that locking was meant to protect.\nA:H - `list_del_init()` on a mount being unmounted leaves a self-referential entry, trapping the unsynchronized traverser in an unkillable in-kernel infinite loop (soft/hard lockup), and the freed-mount dereference produces an oops — Al Viro describes it as \"an oopsable race.\""}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/namespace.c"],"versions":[{"version":"620c266f394932e5decc4b34683a75dfc59dc2f4","lessThan":"6482c3dccbfb8d20e2856ce67c75856859930b3f","status":"affected","versionType":"git"},{"version":"620c266f394932e5decc4b34683a75dfc59dc2f4","lessThan":"287c7d34eedd37af1272dfb3b6e8656f4f026424","status":"affected","versionType":"git"},{"version":"620c266f394932e5decc4b34683a75dfc59dc2f4","lessThan":"1f282cdc1d219c4a557f7009e81bc792820d9d9a","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/namespace.c"],"versions":[{"version":"6.11","status":"affected"},{"version":"0","lessThan":"6.11","status":"unaffected","versionType":"semver"},{"version":"6.12.46","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.15.3","lessThanOrEqual":"6.15.*","status":"unaffected","versionType":"semver"},{"version":"6.16","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.12.46"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.15.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.16"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/6482c3dccbfb8d20e2856ce67c75856859930b3f"},{"url":"https://git.kernel.org/stable/c/287c7d34eedd37af1272dfb3b6e8656f4f026424"},{"url":"https://git.kernel.org/stable/c/1f282cdc1d219c4a557f7009e81bc792820d9d9a"}],"title":"fs/fhandle.c: fix a race in call of has_locked_children()","x_generator":{"engine":"bippy-1.2.0"}}}}