CVE-2025-22074 (GCVE-0-2025-22074)
Vulnerability from cvelistv5
Published
2025-04-16 14:12
Modified
2026-08-05 11:56
Severity ?
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix r_count dec/increment mismatch r_count is only increased when there is an oplock break wait, so r_count inc/decrement are not paired. This can cause r_count to become negative, which can lead to a problem where the ksmbd thread does not terminate.
References
Impacted products
Vendor Product Version
Linux Linux Version: 09aeab68033161cb54f194da93e51a11aee6144b
Version: a4261bbc33fbf99b99c80aa3a2c5097611802980
Version: f17d1c63a76b0fe8e9c78023a86507a3a6d62cfa
Version: 3aa660c059240e0c795217182cf7df32909dd917
Version: 3aa660c059240e0c795217182cf7df32909dd917
Version: 6.6.84   ≤
Version: 6.12.20   ≤
Version: 6.13.8   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/oplock.c"
          ],
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        {
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          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
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              "status": "unaffected",
              "version": "0",
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.23",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.13.11",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.14.*",
              "status": "unaffected",
              "version": "6.14.2",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.15",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.87",
                  "versionStartIncluding": "6.6.84",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.23",
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                  "vulnerable": true
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix r_count dec/increment mismatch\n\nr_count is only increased when there is an oplock break wait,\nso r_count inc/decrement are not paired. This can cause r_count\nto become negative, which can lead to a problem where the ksmbd\nthread does not terminate."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - ksmbd is the in-kernel SMB server listening on TCP/445; the oplock/lease break path is driven entirely by SMB2 CREATE/WRITE/SET_INFO requests sent by a remote peer over the network.\nAC:L - The attacker owns both connections involved (the oplock holder and the breaker) and controls exactly how many unbalanced decrements occur by sending N writes, so `r_count` can be steered to zero or negative deterministically; no condition outside the attacker\u0027s control is needed.\nPR:L - Obtaining a level-II oplock or read-caching lease requires an open file handle, which requires a completed SMB2 session setup and tree connect with valid credentials \u2014 a low-privileged authenticated share user suffices.\nUI:N - The attacker triggers the oplock break itself by writing to or truncating the file from a second connection; no action by any local user or administrator is required.\nS:U - The corruption and its consequences (hung ksmbd kthread, freed ksmbd_conn/transport reuse) remain entirely within the kernel\u0027s own security authority.\nC:H - The underflow lets the connection teardown free `ksmbd_conn`, the transport and the socket while an in-flight work item still dereferences them, and the attacker can reoccupy that slab with request-buffer data, yielding a use-after-free read primitive over kernel memory including session keys and credentials.\nI:H - The same use-after-free gives writes through the stale `work-\u003econn`/`work-\u003esess` pointers and via `ksmbd_conn_write()` into freed and reallocated memory, which is the standard basis for heap-spray-driven control-flow hijacking.\nA:H - A negative `r_count` makes `wait_event(conn-\u003er_count_q, r_count == 0)` unsatisfiable, hanging the `ksmbd:%u` kthread uninterruptibly and permanently leaking the socket, connection and sessions; this is repeatable per connection until resources are exhausted, and the UAF variant additionally causes kernel oopses."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:56:32.474Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/4790bcb269e5d6d88200a67c54ae6d627332a3be"
        },
        {
          "url": "https://git.kernel.org/stable/c/457db486203c90e10c3efc87fd45cc7000b1cd36"
        },
        {
          "url": "https://git.kernel.org/stable/c/20378cf48359f39dee0ef9b61470ebe77bd49c0d"
        },
        {
          "url": "https://git.kernel.org/stable/c/c2ec33d46b4d1c8085dab5d02e00b21f4f0fb8a9"
        },
        {
          "url": "https://git.kernel.org/stable/c/ddb7ea36ba7129c2ed107e2186591128618864e1"
        }
      ],
      "title": "ksmbd: fix r_count dec/increment mismatch",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-22074",
    "datePublished": "2025-04-16T14:12:25.921Z",
    "dateReserved": "2024-12-29T08:45:45.814Z",
    "dateUpdated": "2026-08-05T11:56:32.474Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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