Vulnerability-Lookup

GHSA-F255-X52R-MJQ5

Vulnerability from github – Published: 2025-12-09 18:30 – Updated: 2026-10-30 15:32

Details

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix potential UAF in smb2_close_cached_fid()

find_or_create_cached_dir() could grab a new reference after kref_put() had seen the refcount drop to zero but before cfid_list_lock is acquired in smb2_close_cached_fid(), leading to use-after-free.

Switch to kref_put_lock() so cfid_release() is called with cfid_list_lock held, closing that gap.

Severity

8.8 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2025-40328"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-12-09T16:17:42Z",
    "severity": "HIGH"
  },
  "details": "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.",
  "id": "GHSA-f255-x52r-mjq5",
  "modified": "2026-10-30T15:32:20Z",
  "published": "2025-12-09T18:30:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-40328"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/065bd62412271a2d734810dd50336cae88c54427"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/734e99623c5b65bf2c03e35978a0b980ebc3c2f8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bb3355ce9dcaba1b4a766f98b2ad373cab6cd626"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bdb596ceb4b7c3f28786a33840263728217fbcf5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb52d9c86d70298de0ab7c7953653898cbc0efd6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2025-40328 (GCVE-0-2025-40328)

Vulnerability from cvelistv5 – Published: 2025-12-09 04:09 – Updated: 2026-10-30 12:23

Title

smb: client: fix potential UAF in smb2_close_cached_fid()

Summary

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix potential UAF in smb2_close_cached_fid() find_or_create_cached_dir() could grab a new reference after kref_put() had seen the refcount drop to zero but before cfid_list_lock is acquired in smb2_close_cached_fid(), leading to use-after-free. Switch to kref_put_lock() so cfid_release() is called with cfid_list_lock held, closing that gap.

Severity

8.8 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-15 21:59 UTC

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7018 records in the last 180 days details

References

5 references

URL	Tags
https://git.kernel.org/stable/c/bb3355ce9dcaba1b4…
https://git.kernel.org/stable/c/cb52d9c86d70298de…
https://git.kernel.org/stable/c/065bd62412271a2d7…
https://git.kernel.org/stable/c/bdb596ceb4b7c3f28…
https://git.kernel.org/stable/c/734e99623c5b65bf2…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: ebe98f1447bbccf8228335c62d86af02a0ed23f7 , < bb3355ce9dcaba1b4a766f98b2ad373cab6cd626 (git) Affected: ebe98f1447bbccf8228335c62d86af02a0ed23f7 , < cb52d9c86d70298de0ab7c7953653898cbc0efd6 (git) Affected: ebe98f1447bbccf8228335c62d86af02a0ed23f7 , < 065bd62412271a2d734810dd50336cae88c54427 (git) Affected: ebe98f1447bbccf8228335c62d86af02a0ed23f7 , < bdb596ceb4b7c3f28786a33840263728217fbcf5 (git) Affected: ebe98f1447bbccf8228335c62d86af02a0ed23f7 , < 734e99623c5b65bf2c03e35978a0b980ebc3c2f8 (git)
Linux	Linux	Affected: 6.1 Unaffected: 0 , < 6.1 (semver) Unaffected: 6.1.191 , ≤ 6.1.* (semver) Unaffected: 6.6.117 , ≤ 6.6.* (semver) Unaffected: 6.12.58 , ≤ 6.12.* (semver) Unaffected: 6.17.8 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-40328",
                "options": [
                  {
                    "Exploitation": "none"
                  },
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                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-15T21:59:26.611635Z",
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              "value": "AV:N - The freeing side of the race is driven directly by a remote peer \u2014 `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\u0027d 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\u0027s own security authority \u2014 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-\u003edentry)` 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` \u2014 including `dput()` on a freed dentry and slab corruption \u2014 reliably causing an oops or kernel panic."
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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