{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40328","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T07:20:57.186Z","datePublished":"2025-12-09T04:09:44.876Z","dateUpdated":"2026-08-05T12:09:39.443Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:09:39.443Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix potential UAF in smb2_close_cached_fid()\n\nfind_or_create_cached_dir() could grab a new reference after kref_put()\nhad seen the refcount drop to zero but before cfid_list_lock is acquired\nin smb2_close_cached_fid(), leading to use-after-free.\n\nSwitch to kref_put_lock() so cfid_release() is called with\ncfid_list_lock held, closing that gap."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The freeing side of the race is driven directly by a remote peer — `smb2_is_valid_lease_break()` (fs/smb/client/smb2misc.c:692) processes unsolicited SMB2 lease-break packets from the server and calls `cached_dir_lease_break()`, which clears the lease ref and queues the final `kref_put()`; server-forced reconnects similarly drive `invalidate_all_cached_dirs()`. A malicious, compromised, or MITM'd SMB server therefore triggers the vulnerable refcount transition over the network.\nAC:L - The attacker controls the timing and rate of lease breaks/reconnects and can replay them indefinitely against routine directory activity on the mount, so the narrow window between `refcount_dec_and_test()` and the lock acquisition can be hit reliably by repetition. Race conditions the attacker can retry at will are Low complexity.\nPR:N - A malicious or MITM SMB server needs no credentials or privileges on the victim host; lease-break notifications are unsolicited server-to-client messages processed by the demultiplex thread. In the local variant the trigger is plain rmdir/stat/readdir on an accessible mount, requiring at most an unprivileged account.\nUI:R - Exploitation requires the victim to have the attacker-controlled SMB share mounted and to be performing directory lookups on it so that `find_or_create_cached_dir()` runs concurrently with the release path. The server cannot force that local access itself.\nS:U - The use-after-free is on a kernel slab object (`struct cached_fid`) and the impact stays within the kernel's own security authority — no VM, IOMMU, or sandbox boundary is crossed.\nC:H - A freed `cached_fid` holding `dentry`, `tcon`, `cifs_fid` handles, a mutex and list/work heads can be reallocated and sprayed with attacker-chosen data; the racing thread then reads it and returns cached directory/file_all_info state, giving a path to disclosing kernel memory. Per guidance, use-after-free is scored High for confidentiality.\nI:H - The stale object is written through as well as read (`kref_get`, `last_access_time`, list manipulation, `dput(cfid->dentry)` on a reused pointer, and `SMB2_close()` on stale fid values), so heap grooming turns this into a write primitive over reallocated slab contents and potential control-flow hijack via the embedded `work_struct` function pointers.\nA:H - Losing the race produces a `refcount_t: addition on 0` warning followed by dereference and double-free of the `cached_fid` — including `dput()` on a freed dentry and slab corruption — reliably causing an oops or kernel panic."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/cached_dir.c"],"versions":[{"version":"ebe98f1447bbccf8228335c62d86af02a0ed23f7","lessThan":"cb52d9c86d70298de0ab7c7953653898cbc0efd6","status":"affected","versionType":"git"},{"version":"ebe98f1447bbccf8228335c62d86af02a0ed23f7","lessThan":"065bd62412271a2d734810dd50336cae88c54427","status":"affected","versionType":"git"},{"version":"ebe98f1447bbccf8228335c62d86af02a0ed23f7","lessThan":"bdb596ceb4b7c3f28786a33840263728217fbcf5","status":"affected","versionType":"git"},{"version":"ebe98f1447bbccf8228335c62d86af02a0ed23f7","lessThan":"734e99623c5b65bf2c03e35978a0b980ebc3c2f8","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/smb/client/cached_dir.c"],"versions":[{"version":"6.1","status":"affected"},{"version":"0","lessThan":"6.1","status":"unaffected","versionType":"semver"},{"version":"6.6.117","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.58","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.17.8","lessThanOrEqual":"6.17.*","status":"unaffected","versionType":"semver"},{"version":"6.18","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":"6.1","versionEndExcluding":"6.6.117"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.12.58"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.17.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.18"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/cb52d9c86d70298de0ab7c7953653898cbc0efd6"},{"url":"https://git.kernel.org/stable/c/065bd62412271a2d734810dd50336cae88c54427"},{"url":"https://git.kernel.org/stable/c/bdb596ceb4b7c3f28786a33840263728217fbcf5"},{"url":"https://git.kernel.org/stable/c/734e99623c5b65bf2c03e35978a0b980ebc3c2f8"}],"title":"smb: client: fix potential UAF in smb2_close_cached_fid()","x_generator":{"engine":"bippy-1.2.0"}}}}