CVE-2025-40249 (GCVE-0-2025-40249)

Vulnerability from cvelistv5 – Published: 2025-12-04 16:08 – Updated: 2026-08-05 12:08
VLAI
Title
gpio: cdev: make sure the cdev fd is still active before emitting events
Summary
In the Linux kernel, the following vulnerability has been resolved: gpio: cdev: make sure the cdev fd is still active before emitting events With the final call to fput() on a file descriptor, the release action may be deferred and scheduled on a work queue. The reference count of that descriptor is still zero and it must not be used. It's possible that a GPIO change, we want to notify the user-space about, happens AFTER the reference count on the file descriptor associated with the character device went down to zero but BEFORE the .release() callback was called from the workqueue and so BEFORE we unregistered from the notifier. Using the regular get_file() routine in this situation triggers the following warning: struct file::f_count incremented from zero; use-after-free condition present! So use the get_file_active() variant that will return NULL on file descriptors that have been or are being released.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 40b7c49950bd56c984b1f6722f865b922879260e , < dccc6daa8afa0f64c432e4c867f275747e3415e1 (git)
Affected: 40b7c49950bd56c984b1f6722f865b922879260e , < d4cd0902c156b2ca60fdda8cd8b5bcb4b0e9ed64 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.13
Unaffected: 0 , < 6.13 (semver)
Unaffected: 6.17.10 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpio/gpiolib-cdev.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "dccc6daa8afa0f64c432e4c867f275747e3415e1",
              "status": "affected",
              "version": "40b7c49950bd56c984b1f6722f865b922879260e",
              "versionType": "git"
            },
            {
              "lessThan": "d4cd0902c156b2ca60fdda8cd8b5bcb4b0e9ed64",
              "status": "affected",
              "version": "40b7c49950bd56c984b1f6722f865b922879260e",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpio/gpiolib-cdev.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.13"
            },
            {
              "lessThan": "6.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.10",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngpio: cdev: make sure the cdev fd is still active before emitting events\n\nWith the final call to fput() on a file descriptor, the release action\nmay be deferred and scheduled on a work queue. The reference count of\nthat descriptor is still zero and it must not be used. It\u0027s possible\nthat a GPIO change, we want to notify the user-space about, happens\nAFTER the reference count on the file descriptor associated with the\ncharacter device went down to zero but BEFORE the .release() callback\nwas called from the workqueue and so BEFORE we unregistered from the\nnotifier.\n\nUsing the regular get_file() routine in this situation triggers the\nfollowing warning:\n\n  struct file::f_count incremented from zero; use-after-free condition present!\n\nSo use the get_file_active() variant that will return NULL on file\ndescriptors that have been or are being released."
        }
      ],
      "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 vulnerability is reached through the GPIO character device `/dev/gpiochipN` via `open()`, `ioctl()` and `close()`, requiring local access to the system. There is no network-facing path to the GPIO line-state notifier chain.\nAC:L - The attacker controls both sides of the race \u2014 one thread loops open/`GPIO_V2_GET_LINEINFO_WATCH_IOCTL`/close while another loops line request/release/set-config to fire `gpiod_line_state_notify()` \u2014 and can retry indefinitely; the fput-to-release window can additionally be stretched to a full jiffy by forcing the `schedule_delayed_work(\u0026delayed_fput_work, 1)` path, and the reporter hit the condition during normal operation.\nPR:L - No capability check exists anywhere in `gpio_chrdev_open()` or `gpio_ioctl()` \u2014 only file permissions on `/dev/gpiochipN`, which embedded, IoT, automotive and Raspberry-Pi-class deployments routinely grant to a non-root `gpio` group or to unprivileged libgpiod control daemons. A basic unprivileged local account with that group membership is sufficient.\nUI:N - The attacker performs every step itself \u2014 opening the chardev, arming the line watch, generating the line-state change, and closing the fd. No victim action or cooperation is needed.\nS:U - The use-after-free corrupts kernel heap memory within the same kernel security authority; there is no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - This is a use-after-free on both the `struct file` and the ~9.4 KB `gpio_chardev_data` object; a resprayed `cdev` lets `kfifo_in_spinlocked()` and `fput(cdev-\u003efp)` read through attacker-chosen pointers, and `wake_up_poll()` on the freed wait queue yields a controlled call primitive, enabling arbitrary kernel memory disclosure.\nI:H - The queued work writes a 288-byte event record (with an attacker-supplied 32-byte consumer label) through the freed object\u0027s kfifo `data` pointer and performs a refcount decrement through a dangling `struct file *`, giving arbitrary-write and function-pointer-hijack primitives suitable for privilege escalation.\nA:H - In the common case the bug produces a `refcount_t` WARN (\"f_count incremented from zero; use-after-free condition present!\") \u2014 an immediate panic under `panic_on_warn` \u2014 followed by use-after-free accesses to a freed spinlock, kfifo and wait queue that reliably oops or panic the kernel, and the sequence is repeatable at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:08:51.621Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/dccc6daa8afa0f64c432e4c867f275747e3415e1"
        },
        {
          "url": "https://git.kernel.org/stable/c/d4cd0902c156b2ca60fdda8cd8b5bcb4b0e9ed64"
        }
      ],
      "title": "gpio: cdev: make sure the cdev fd is still active before emitting events",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40249",
    "datePublished": "2025-12-04T16:08:12.206Z",
    "dateReserved": "2025-04-16T07:20:57.181Z",
    "dateUpdated": "2026-08-05T12:08:51.621Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-40249",
      "date": "2026-10-29",
      "epss": "0.00144",
      "percentile": "0.03691"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "drivers/gpio/gpiolib-cdev.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "dccc6daa8afa0f64c432e4c867f275747e3415e1",
                    "status": "affected",
                    "version": "40b7c49950bd56c984b1f6722f865b922879260e",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "d4cd0902c156b2ca60fdda8cd8b5bcb4b0e9ed64",
                    "status": "affected",
                    "version": "40b7c49950bd56c984b1f6722f865b922879260e",
                    "versionType": "git"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "drivers/gpio/gpiolib-cdev.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "6.13"
                  },
                  {
                    "lessThan": "6.13",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.17.*",
                    "status": "unaffected",
                    "version": "6.17.10",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "6.18",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngpio: cdev: make sure the cdev fd is still active before emitting events\n\nWith the final call to fput() on a file descriptor, the release action\nmay be deferred and scheduled on a work queue. The reference count of\nthat descriptor is still zero and it must not be used. It\u0027s possible\nthat a GPIO change, we want to notify the user-space about, happens\nAFTER the reference count on the file descriptor associated with the\ncharacter device went down to zero but BEFORE the .release() callback\nwas called from the workqueue and so BEFORE we unregistered from the\nnotifier.\n\nUsing the regular get_file() routine in this situation triggers the\nfollowing warning:\n\n  struct file::f_count incremented from zero; use-after-free condition present!\n\nSo use the get_file_active() variant that will return NULL on file\ndescriptors that have been or are being released."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ngpio: cdev: asegurar que el fd del cdev sigue activo antes de emitir eventos\n\nCon la llamada final a fput() en un descriptor de archivo, la acci\u00f3n de liberaci\u00f3n puede ser diferida y programada en una cola de trabajo. El contador de referencias de ese descriptor sigue siendo cero y no debe ser usado. Es posible que un cambio de GPIO, sobre el cual queremos notificar al espacio de usuario, ocurra DESPU\u00c9S de que el contador de referencias en el descriptor de archivo asociado con el dispositivo de caracteres baj\u00f3 a cero, pero ANTES de que la devoluci\u00f3n de llamada .release() fuera invocada desde la cola de trabajo y, por lo tanto, ANTES de que nos desregistr\u00e1ramos del notificador.\n\nUsar la rutina get_file() regular en esta situaci\u00f3n desencadena la siguiente advertencia:\n\n  struct file::f_count incrementado desde cero; \u00a1condici\u00f3n de uso despu\u00e9s de liberaci\u00f3n presente!\n\nAs\u00ed que usar la variante get_file_active() que devolver\u00e1 NULL en descriptores de archivo que han sido o est\u00e1n siendo liberados."
          }
        ],
        "id": "CVE-2025-40249",
        "lastModified": "2026-10-19T21:10:00.160",
        "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": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ]
        },
        "published": "2025-12-04T16:16:18.380",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/d4cd0902c156b2ca60fdda8cd8b5bcb4b0e9ed64"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/dccc6daa8afa0f64c432e4c867f275747e3415e1"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Deferred"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-30T08:43:07+00:00",
      "cve": "CVE-2025-40249",
      "id": "CVE-2025-40249",
      "initial_release_date": "2025-12-04T00:00:00+00:00",
      "product_status:fixed": "309",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Kernel: Use-after-free in GPIO character device allows privilege escalation or denial of service",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40249.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-28T16:54:35Z",
      "cve": "CVE-2025-40249",
      "id": "CVE-2025-40249",
      "initial_release_date": "2025-12-05T00:25:32Z",
      "product_status:known_not_affected": "515",
      "product_status:recommended": "42",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-40249",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-40249.json",
      "version": "10"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.