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GHSA-HXV7-WMRF-Q57M

Vulnerability from github – Published: 2025-05-20 18:30 – Updated: 2025-11-14 18:31

Details

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

smb: client: Avoid race in open_cached_dir with lease breaks

A pre-existing valid cfid returned from find_or_create_cached_dir might race with a lease break, meaning open_cached_dir doesn't consider it valid, and thinks it's newly-constructed. This leaks a dentry reference if the allocation occurs before the queued lease break work runs.

Avoid the race by extending holding the cfid_list_lock across find_or_create_cached_dir and when the result is checked.

Severity

5.5 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2025-37954"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-05-20T16:15:33Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: Avoid race in open_cached_dir with lease breaks\n\nA pre-existing valid cfid returned from find_or_create_cached_dir might\nrace with a lease break, meaning open_cached_dir doesn\u0027t consider it\nvalid, and thinks it\u0027s newly-constructed. This leaks a dentry reference\nif the allocation occurs before the queued lease break work runs.\n\nAvoid the race by extending holding the cfid_list_lock across\nfind_or_create_cached_dir and when the result is checked.",
  "id": "GHSA-hxv7-wmrf-q57m",
  "modified": "2025-11-14T18:31:18Z",
  "published": "2025-05-20T18:30:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-37954"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2407265dc32bc8cc45b62a612c2a214ba9038e8b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2ed98e89ebc2e1bc73534dc3c18cb7843a889ff9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3ca02e63edccb78ef3659bebc68579c7224a6ca2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/571dcf3d27b24800c171aea7b5e04ff06d10e2e9"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2025-37954 (GCVE-0-2025-37954)

Vulnerability from cvelistv5 – Published: 2025-05-20 16:01 – Updated: 2026-08-05 11:58

Title

smb: client: Avoid race in open_cached_dir with lease breaks

Summary

In the Linux kernel, the following vulnerability has been resolved: smb: client: Avoid race in open_cached_dir with lease breaks A pre-existing valid cfid returned from find_or_create_cached_dir might race with a lease break, meaning open_cached_dir doesn't consider it valid, and thinks it's newly-constructed. This leaks a dentry reference if the allocation occurs before the queued lease break work runs. Avoid the race by extending holding the cfid_list_lock across find_or_create_cached_dir and when the result is checked.

Severity

7.5 (High)


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

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/2ed98e89ebc2e1bc7…
https://git.kernel.org/stable/c/571dcf3d27b24800c…
https://git.kernel.org/stable/c/2407265dc32bc8cc4…
https://git.kernel.org/stable/c/3ca02e63edccb78ef…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 81ba10959970d15c388bf29866b01b62f387e6a3 , < 2ed98e89ebc2e1bc73534dc3c18cb7843a889ff9 (git) Affected: 81ba10959970d15c388bf29866b01b62f387e6a3 , < 571dcf3d27b24800c171aea7b5e04ff06d10e2e9 (git) Affected: 81ba10959970d15c388bf29866b01b62f387e6a3 , < 2407265dc32bc8cc45b62a612c2a214ba9038e8b (git) Affected: 81ba10959970d15c388bf29866b01b62f387e6a3 , < 3ca02e63edccb78ef3659bebc68579c7224a6ca2 (git) Affected: 436be190fbf81e5d84040dabf9cb7be06a94dc5d (git) Affected: 6.5.10 , < 6.6 (semver)
Linux	Linux	Affected: 6.6 Unaffected: 0 , < 6.6 (semver) Unaffected: 6.6.91 , ≤ 6.6.* (semver) Unaffected: 6.12.29 , ≤ 6.12.* (semver) Unaffected: 6.14.7 , ≤ 6.14.* (semver) Unaffected: 6.15 , ≤ * (original_commit_for_fix)

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              "lang": "en",
              "value": "AV:N - The race is driven by an unsolicited SMB2 lease-break packet from the remote server, dispatched straight from the cifs demultiplex thread into cached_dir_lease_break() (fs/smb/client/smb2misc.c:655) with no pending request. A malicious/compromised SMB server, or an off-path attacker injecting frames on an unsigned SMB connection, controls exactly when that half of the race fires.\nAC:L - The attacker controls both sides \u2014 the server chooses when and how often to send lease breaks (unlimited retries, one per re-cached directory), while the client\u0027s routine stat()/getdents() traffic, which the server can itself provoke by breaking leases to force re-opens, repeatedly traverses the unlocked window. The same class of race in this file was reproduced by its author with two ordinary shell loops.\nPR:N - The attacking SMB server holds no privileges or credentials on the victim client; it merely answers a share the client has already mounted. The local half needs nothing beyond stat() or readdir() on the mount, available to any unprivileged account with no capabilities.\nUI:N - The mount is a pre-existing configuration, not an exploit-time action, and no deliberate victim participation is needed \u2014 ordinary background directory access from any process supplies the local half, and the server can force re-opens on demand by breaking the lease.\nS:U - The leaked dentry/inode references, corrupted superblock teardown and crash are all confined to the client kernel\u0027s own security authority. No VM, IOMMU or sandbox boundary is crossed.\nC:N - The defect is a lost reference count; no memory is read out of bounds and no kernel data is copied to the attacker. The only pointer surfaced is in a WARN message, which is %p-hashed and requires dmesg access.\nI:N - The attacker gains no write primitive \u2014 nothing attacker-controlled is stored anywhere, and the cfid kref accounting remains balanced in every interleaving I traced, so no double-free or type confusion is reachable.\nA:H - Each won race permanently leaks a dentry, its inode and an open server handle, and the affected mount can never be torn down: unmount hits WARN(1, \"BUG: Dentry ... still in use\") in umount_check() and then \"VFS: Busy inodes after unmount\", which is a hard BUG()/oops under CONFIG_BUG_ON_DATA_CORRUPTION and a panic under panic_on_warn. Otherwise the superblock is freed with live VFS_PTR_POISON\u0027d inodes that crash on any later access, on top of unbounded, unreclaimable memory growth."
            }
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        "dateUpdated": "2026-08-05T11:58:37.074Z",
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    "dateReserved": "2025-04-16T04:51:23.973Z",
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    "state": "PUBLISHED"
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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.

Detection rules are retrieved from Rulezet.

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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