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CVE-2026-98258

Estado: RecibidaSin puntuar—

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

posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list

Kijo analyzed another race in the POSIX CPU timer code:

Commit bf635681c906 converted cpu_timer::firing from a tristate value to a boolean. This lost the distinction between "not owned by the firing list" and "still owned, but delivery was canceled". The resulting race is:

The firing bit is clearly the wrong indicator since that commit.

Check whether the timer is queued on the expiry list or not instead. If it is queued clear the firing bit to prevent signal delivery as before and return TIMER_RETRY so the caller unlocks the timer which allows the expiry code to make progress and remove it from the list.

Detalles técnicos trazas, registros y código del informe original
    expiry handler              timer_settime()        timer_delete()
    --------------              ---------------        --------------
    collect timer onto
    private firing list
    firing = true
                                observes firing = true
                                firing = false
                                return TIMER_RETRY
                                wait for handler
                                                       observes firing = false
                                                       finish deletion
                                                       unhash and free timer
    resume list traversal
    read freed elist.next
    -> UAF

CVSS

NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux KernelAI

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-98258",
  "cveTags": [],
  "metrics": {},
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "bf635681c906ad056d1fda325de8d1c12c9f8201",
              "lessThan": "9971dac1a77845ff467146915fcbb9170f6a8209",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "bf635681c906ad056d1fda325de8d1c12c9f8201",
              "lessThan": "4336e3f47d9d516441066e9a65eaf076790d8d45",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "bf635681c906ad056d1fda325de8d1c12c9f8201",
              "lessThan": "c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "kernel/time/posix-cpu-timers.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.13"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.13",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.18.54",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.8",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc4",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "kernel/time/posix-cpu-timers.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-10-06T09:18:14.737",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/4336e3f47d9d516441066e9a65eaf076790d8d45",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9971dac1a77845ff467146915fcbb9170f6a8209",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nposix-cpu-timers: Prevent freeing a timer which is queued on the expiry list\n\nKijo analyzed another race in the POSIX CPU timer code:\n\nCommit bf635681c906 converted cpu_timer::firing from a tristate value to a\nboolean. This lost the distinction between \"not owned by the firing list\"\nand \"still owned, but delivery was canceled\". The resulting race is:\n\n    expiry handler              timer_settime()        timer_delete()\n    --------------              ---------------        --------------\n    collect timer onto\n    private firing list\n    firing = true\n                                observes firing = true\n                                firing = false\n                                return TIMER_RETRY\n                                wait for handler\n                                                       observes firing = false\n                                                       finish deletion\n                                                       unhash and free timer\n    resume list traversal\n    read freed elist.next\n    -> UAF\n\nThe firing bit is clearly the wrong indicator since that commit.\n\nCheck whether the timer is queued on the expiry list or not instead. If it\nis queued clear the firing bit to prevent signal delivery as before and\nreturn TIMER_RETRY so the caller unlocks the timer which allows the expiry\ncode to make progress and remove it from the list."
    }
  ],
  "lastModified": "2026-10-06T09:18:14.737",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}