{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "37745918e0e7575bc40f38da93a99b9fa6406224"
            },
            {
              "fixed": "996c24377eea4d4506b7c3ccbbf1e490440b5e0b"
            },
            {
              "fixed": "1395327a96614885552bae5fbb650e6dd182d49b"
            },
            {
              "fixed": "c1078130a4cd7e738f4b73afe99b3e68cbfbf884"
            },
            {
              "fixed": "70d28bfcd6224eed75986b3b987b997e59643fa4"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.12.0"
            },
            {
              "fixed": "6.12.101"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.42"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.1.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68200.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: timer: don't re-enter an instance callback that is still running\n\nThe userspace-driven timer (utimer) TRIGGER ioctl calls\nsnd_timer_interrupt() directly with no serialization, so two threads\ntriggering the same utimer can run snd_timer_interrupt() on one\nsnd_timer concurrently.\n\nsnd_timer_process_callbacks() drops timer-\u003elock around each instance\ncallback and marks the in-flight callback with the single\nSNDRV_TIMER_IFLG_CALLBACK bit; snd_timer_close_locked() waits on that\nbit to drain an in-flight callback before freeing the instance. The bit\ncannot represent two concurrent callbacks: when a second interrupt\nre-queues an instance whose callback is still running, both run at once,\nthe first to finish clears the bit, and the close-path drain then frees\nthe instance (and its callback_data) while the other callback is still\nlive - a use-after-free reachable by any user able to open\n/dev/snd/timer, both via a user timer instance and via a sequencer queue\ntimer bound to the utimer.\n\nsnd_timer_interrupt() sets IFLG_CALLBACK before dropping timer-\u003elock, so\na concurrent interrupt already observes it under the lock. Skip\nre-queuing an instance (and its slaves) to the ack/sack list while its\ncallback is in flight; the accumulated pticks are delivered on the next\ntick, so no event is lost.",
  "id": "CVE-2026-68200",
  "modified": "2026-08-15T11:31:17.730623478Z",
  "published": "2026-08-10T12:00:19.253Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1395327a96614885552bae5fbb650e6dd182d49b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/70d28bfcd6224eed75986b3b987b997e59643fa4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/996c24377eea4d4506b7c3ccbbf1e490440b5e0b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c1078130a4cd7e738f4b73afe99b3e68cbfbf884"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68200.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68200"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "ALSA: timer: don't re-enter an instance callback that is still running"
}