Vulnerability-Lookup

FKIE_CVE-2025-39863

Vulnerability from fkie_nvd - Published: 2025-09-19 16:15 - Updated: 2026-06-19 13:16

Severity

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8 (High) - CVSS:3.1/AV:L/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: wifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work The brcmf_btcoex_detach() only shuts down the btcoex timer, if the flag timer_on is false. However, the brcmf_btcoex_timerfunc(), which runs as timer handler, sets timer_on to false. This creates critical race conditions: 1.If brcmf_btcoex_detach() is called while brcmf_btcoex_timerfunc() is executing, it may observe timer_on as false and skip the call to timer_shutdown_sync(). 2.The brcmf_btcoex_timerfunc() may then reschedule the brcmf_btcoex_info worker after the cancel_work_sync() has been executed, resulting in use-after-free bugs. The use-after-free bugs occur in two distinct scenarios, depending on the timing of when the brcmf_btcoex_info struct is freed relative to the execution of its worker thread. Scenario 1: Freed before the worker is scheduled The brcmf_btcoex_info is deallocated before the worker is scheduled. A race condition can occur when schedule_work(&bt_local->work) is called after the target memory has been freed. The sequence of events is detailed below: CPU0 | CPU1 brcmf_btcoex_detach | brcmf_btcoex_timerfunc | bt_local->timer_on = false; if (cfg->btcoex->timer_on) | ... | cancel_work_sync(); | ... | kfree(cfg->btcoex); // FREE | | schedule_work(&bt_local->work); // USE Scenario 2: Freed after the worker is scheduled The brcmf_btcoex_info is freed after the worker has been scheduled but before or during its execution. In this case, statements within the brcmf_btcoex_handler() — such as the container_of macro and subsequent dereferences of the brcmf_btcoex_info object will cause a use-after-free access. The following timeline illustrates this scenario: CPU0 | CPU1 brcmf_btcoex_detach | brcmf_btcoex_timerfunc | bt_local->timer_on = false; if (cfg->btcoex->timer_on) | ... | cancel_work_sync(); | ... | schedule_work(); // Reschedule | kfree(cfg->btcoex); // FREE | brcmf_btcoex_handler() // Worker /* | btci = container_of(....); // USE The kfree() above could | ... also occur at any point | btci-> // USE during the worker's execution| */ | To resolve the race conditions, drop the conditional check and call timer_shutdown_sync() directly. It can deactivate the timer reliably, regardless of its current state. Once stopped, the timer_on state is then set to false.

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/2f6fbc8e04ca1d1d5c560be694199f847229c625	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/3e789f8475f6c857c88de5c5bf4b24b11a477dd7	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/9cb83d4be0b9b697eae93d321e0da999f9cdfcfc	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ae58f70bde0433f27ef4b388ab50634736607bf6
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/c75600e69e66a751cc046cd9c407b942f298d852
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/f1150153c4e5940fe49ab51136343c5b4fe49d63	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	6.17
linux	linux_kernel	6.17
linux	linux_kernel	6.17
linux	linux_kernel	6.17

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c75600e69e66a751cc046cd9c407b942f298d852",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            },
            {
              "lessThan": "ae58f70bde0433f27ef4b388ab50634736607bf6",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            },
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              "versionType": "git"
            },
            {
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              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "2f6fbc8e04ca1d1d5c560be694199f847229c625",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            },
            {
              "lessThan": "9cb83d4be0b9b697eae93d321e0da999f9cdfcfc",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.10"
            },
            {
              "lessThan": "3.10",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.167",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.105",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.46",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "D5818F4E-9CA3-4FE9-8A75-A6ACE2B108FC",
              "versionEndExcluding": "6.6.105",
              "versionStartIncluding": "3.10",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "F7E2B332-E920-4CAC-B400-288602DB6F16",
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              "versionStartIncluding": "6.7",
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            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*",
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              "matchCriteriaId": "C730CD9A-D969-4A8E-9522-162AAF7C0EE9",
              "vulnerable": true
            },
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              "matchCriteriaId": "39982C4B-716E-4B2F-8196-FA301F47807D",
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              "matchCriteriaId": "340BEEA9-D70D-4290-B502-FBB1032353B1",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work\n\nThe brcmf_btcoex_detach() only shuts down the btcoex timer, if the\nflag timer_on is false. However, the brcmf_btcoex_timerfunc(), which\nruns as timer handler, sets timer_on to false. This creates critical\nrace conditions:\n\n1.If brcmf_btcoex_detach() is called while brcmf_btcoex_timerfunc()\nis executing, it may observe timer_on as false and skip the call to\ntimer_shutdown_sync().\n\n2.The brcmf_btcoex_timerfunc() may then reschedule the brcmf_btcoex_info\nworker after the cancel_work_sync() has been executed, resulting in\nuse-after-free bugs.\n\nThe use-after-free bugs occur in two distinct scenarios, depending on\nthe timing of when the brcmf_btcoex_info struct is freed relative to\nthe execution of its worker thread.\n\nScenario 1: Freed before the worker is scheduled\n\nThe brcmf_btcoex_info is deallocated before the worker is scheduled.\nA race condition can occur when schedule_work(\u0026bt_local-\u003ework) is\ncalled after the target memory has been freed. The sequence of events\nis detailed below:\n\nCPU0                           | CPU1\nbrcmf_btcoex_detach            | brcmf_btcoex_timerfunc\n                               |   bt_local-\u003etimer_on = false;\n  if (cfg-\u003ebtcoex-\u003etimer_on)   |\n    ...                        |\n  cancel_work_sync();          |\n  ...                          |\n  kfree(cfg-\u003ebtcoex); // FREE  |\n                               |   schedule_work(\u0026bt_local-\u003ework); // USE\n\nScenario 2: Freed after the worker is scheduled\n\nThe brcmf_btcoex_info is freed after the worker has been scheduled\nbut before or during its execution. In this case, statements within\nthe brcmf_btcoex_handler() \u2014 such as the container_of macro and\nsubsequent dereferences of the brcmf_btcoex_info object will cause\na use-after-free access. The following timeline illustrates this\nscenario:\n\nCPU0                            | CPU1\nbrcmf_btcoex_detach             | brcmf_btcoex_timerfunc\n                                |   bt_local-\u003etimer_on = false;\n  if (cfg-\u003ebtcoex-\u003etimer_on)    |\n    ...                         |\n  cancel_work_sync();           |\n  ...                           |   schedule_work(); // Reschedule\n                                |\n  kfree(cfg-\u003ebtcoex); // FREE   |   brcmf_btcoex_handler() // Worker\n  /*                            |     btci = container_of(....); // USE\n   The kfree() above could      |     ...\n   also occur at any point      |     btci-\u003e // USE\n   during the worker\u0027s execution|\n   */                           |\n\nTo resolve the race conditions, drop the conditional check and call\ntimer_shutdown_sync() directly. It can deactivate the timer reliably,\nregardless of its current state. Once stopped, the timer_on state is\nthen set to false."
    }
  ],
  "id": "CVE-2025-39863",
  "lastModified": "2026-06-19T13:16:22.500",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2025-39863",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-01-14T19:23:53.735650Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2025-09-19T16:15:45.310",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/2f6fbc8e04ca1d1d5c560be694199f847229c625"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/3e789f8475f6c857c88de5c5bf4b24b11a477dd7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/9cb83d4be0b9b697eae93d321e0da999f9cdfcfc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ae58f70bde0433f27ef4b388ab50634736607bf6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c75600e69e66a751cc046cd9c407b942f298d852"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/f1150153c4e5940fe49ab51136343c5b4fe49d63"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}

CVE-2025-39863 (GCVE-0-2025-39863)

Vulnerability from cvelistv5 – Published: 2025-09-19 15:26 – Updated: 2026-08-05 12:05

Title

wifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work

Summary

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/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 2026-01-14 19:23 UTC

CWE

CWE-416 - Use After Free

Assigner

Linux mitre root Scorecard

References

6 references

URL	Tags
https://git.kernel.org/stable/c/c75600e69e66a751c…
https://git.kernel.org/stable/c/ae58f70bde0433f27…
https://git.kernel.org/stable/c/f1150153c4e5940fe…
https://git.kernel.org/stable/c/3e789f8475f6c857c…
https://git.kernel.org/stable/c/2f6fbc8e04ca1d1d5…
https://git.kernel.org/stable/c/9cb83d4be0b9b697e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < c75600e69e66a751cc046cd9c407b942f298d852 (git) Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < ae58f70bde0433f27ef4b388ab50634736607bf6 (git) Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < f1150153c4e5940fe49ab51136343c5b4fe49d63 (git) Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < 3e789f8475f6c857c88de5c5bf4b24b11a477dd7 (git) Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < 2f6fbc8e04ca1d1d5c560be694199f847229c625 (git) Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < 9cb83d4be0b9b697eae93d321e0da999f9cdfcfc (git)
Linux	Linux	Affected: 3.10 Unaffected: 0 , < 3.10 (semver) Unaffected: 5.15.210 , ≤ 5.15.* (semver) Unaffected: 6.1.167 , ≤ 6.1.* (semver) Unaffected: 6.6.105 , ≤ 6.6.* (semver) Unaffected: 6.12.46 , ≤ 6.12.* (semver) Unaffected: 6.16.6 , ≤ 6.16.* (semver) Unaffected: 6.17 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "LOCAL",
              "availabilityImpact": "HIGH",
              "baseScore": 7.8,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "HIGH",
              "privilegesRequired": "LOW",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2025-39863",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-01-14T19:23:53.735650Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-416",
                "description": "CWE-416 Use After Free",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-01-14T19:33:11.612Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c75600e69e66a751cc046cd9c407b942f298d852",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            },
            {
              "lessThan": "ae58f70bde0433f27ef4b388ab50634736607bf6",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            },
            {
              "lessThan": "f1150153c4e5940fe49ab51136343c5b4fe49d63",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            },
            {
              "lessThan": "3e789f8475f6c857c88de5c5bf4b24b11a477dd7",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            },
            {
              "lessThan": "2f6fbc8e04ca1d1d5c560be694199f847229c625",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            },
            {
              "lessThan": "9cb83d4be0b9b697eae93d321e0da999f9cdfcfc",
              "status": "affected",
              "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.10"
            },
            {
              "lessThan": "3.10",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.167",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.105",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.46",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.210",
                  "versionStartIncluding": "3.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.167",
                  "versionStartIncluding": "3.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.105",
                  "versionStartIncluding": "3.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.46",
                  "versionStartIncluding": "3.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16.6",
                  "versionStartIncluding": "3.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17",
                  "versionStartIncluding": "3.10",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work\n\nThe brcmf_btcoex_detach() only shuts down the btcoex timer, if the\nflag timer_on is false. However, the brcmf_btcoex_timerfunc(), which\nruns as timer handler, sets timer_on to false. This creates critical\nrace conditions:\n\n1.If brcmf_btcoex_detach() is called while brcmf_btcoex_timerfunc()\nis executing, it may observe timer_on as false and skip the call to\ntimer_shutdown_sync().\n\n2.The brcmf_btcoex_timerfunc() may then reschedule the brcmf_btcoex_info\nworker after the cancel_work_sync() has been executed, resulting in\nuse-after-free bugs.\n\nThe use-after-free bugs occur in two distinct scenarios, depending on\nthe timing of when the brcmf_btcoex_info struct is freed relative to\nthe execution of its worker thread.\n\nScenario 1: Freed before the worker is scheduled\n\nThe brcmf_btcoex_info is deallocated before the worker is scheduled.\nA race condition can occur when schedule_work(\u0026bt_local-\u003ework) is\ncalled after the target memory has been freed. The sequence of events\nis detailed below:\n\nCPU0                           | CPU1\nbrcmf_btcoex_detach            | brcmf_btcoex_timerfunc\n                               |   bt_local-\u003etimer_on = false;\n  if (cfg-\u003ebtcoex-\u003etimer_on)   |\n    ...                        |\n  cancel_work_sync();          |\n  ...                          |\n  kfree(cfg-\u003ebtcoex); // FREE  |\n                               |   schedule_work(\u0026bt_local-\u003ework); // USE\n\nScenario 2: Freed after the worker is scheduled\n\nThe brcmf_btcoex_info is freed after the worker has been scheduled\nbut before or during its execution. In this case, statements within\nthe brcmf_btcoex_handler() \u2014 such as the container_of macro and\nsubsequent dereferences of the brcmf_btcoex_info object will cause\na use-after-free access. The following timeline illustrates this\nscenario:\n\nCPU0                            | CPU1\nbrcmf_btcoex_detach             | brcmf_btcoex_timerfunc\n                                |   bt_local-\u003etimer_on = false;\n  if (cfg-\u003ebtcoex-\u003etimer_on)    |\n    ...                         |\n  cancel_work_sync();           |\n  ...                           |   schedule_work(); // Reschedule\n                                |\n  kfree(cfg-\u003ebtcoex); // FREE   |   brcmf_btcoex_handler() // Worker\n  /*                            |     btci = container_of(....); // USE\n   The kfree() above could      |     ...\n   also occur at any point      |     btci-\u003e // USE\n   during the worker\u0027s execution|\n   */                           |\n\nTo resolve the race conditions, drop the conditional check and call\ntimer_shutdown_sync() directly. It can deactivate the timer reliably,\nregardless of its current state. Once stopped, the timer_on state is\nthen set to false."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The race is armed through a local nl80211/netlink command (NL80211_CMD_CRIT_PROTOCOL_START) on the local wireless device and freed through a local driver teardown/bus-reset path; no remote or adjacent-network frame reaches `brcmf_btcoex_detach()` or arms the btcoex timer directly. Although an adjacent attacker can induce the free side by halting the firmware (`BRCMF_D2H_DEV_FWHALT` \u2192 `brcmf_fw_crashed()` \u2192 `brcmf_bus_reset()`), a single attacker capable of both halves of the race operates locally.\nAC:L - The attacker controls both sides: the crit-proto `duration` makes the handler arm the timer at a deterministic `jiffies + 2s`, so the callback\u0027s execution moment is known in advance, and the same actor drives the teardown (bus reset / driver unbind / firmware halt) to land inside it. The attempt is cheap to repeat in a loop until the window is hit, and the freed `kmalloc-192` object can be sprayed with standard heap-grooming syscalls.\nPR:L - `NL80211_CMD_CRIT_PROTOCOL_START` carries `GENL_UNS_ADMIN_PERM` (CAP_NET_ADMIN), which on Android and embedded targets is held by the confined non-root Wi-Fi/supplicant service account rather than by real root in the init namespace, and the free side can be reached without root by making the firmware halt. Basic account-level access with that delegated network capability is sufficient, so this is Low rather than High.\nUI:N - The attacker issues the crit-proto start and triggers the teardown itself; no victim needs to mount a filesystem, open a file, or take any other action for the use-after-free to occur.\nS:U - The freed object, the corrupted slab, and the hijacked workqueue dispatch all live within the kernel\u0027s own security authority, with no crossing into a hypervisor, IOMMU, or other protection domain.\nC:H - The use-after-free lets the attacker reoccupy the freed `brcmf_btcoex_info` slot, after which `brcmf_btcoex_handler()` dereferences attacker-chosen `btci-\u003evif`, `btci-\u003evif-\u003eifp`, and `btci-\u003ecfg-\u003epub` pointers, yielding an arbitrary kernel-memory read primitive and disclosure of kernel addresses.\nI:H - `process_one_work()` loads `work-\u003efunc` out of the freed structure and calls it (`worker-\u003ecurrent_func = work-\u003efunc; worker-\u003ecurrent_func(work);`), so a resprayed slot gives a controlled indirect call, and `schedule_work()` on freed memory additionally corrupts worker-pool list linkage \u2014 a full control-flow-hijack and arbitrary-write primitive.\nA:H - Even without successful grooming, scheduling and executing work on a kfree\u0027d object dereferences poisoned/recycled memory and reliably produces a KASAN splat, oops, or kernel panic, taking the system down."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:05:43.455Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c75600e69e66a751cc046cd9c407b942f298d852"
        },
        {
          "url": "https://git.kernel.org/stable/c/ae58f70bde0433f27ef4b388ab50634736607bf6"
        },
        {
          "url": "https://git.kernel.org/stable/c/f1150153c4e5940fe49ab51136343c5b4fe49d63"
        },
        {
          "url": "https://git.kernel.org/stable/c/3e789f8475f6c857c88de5c5bf4b24b11a477dd7"
        },
        {
          "url": "https://git.kernel.org/stable/c/2f6fbc8e04ca1d1d5c560be694199f847229c625"
        },
        {
          "url": "https://git.kernel.org/stable/c/9cb83d4be0b9b697eae93d321e0da999f9cdfcfc"
        }
      ],
      "title": "wifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39863",
    "datePublished": "2025-09-19T15:26:33.069Z",
    "dateReserved": "2025-04-16T07:20:57.143Z",
    "dateUpdated": "2026-08-05T12:05:43.455Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

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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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FKIE_CVE-2025-39863

CVE-2025-39863 (GCVE-0-2025-39863)

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