CVE-2026-89979

Estado: RecibidaAlta (7.8)—

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

ALSA: pcm: Fix race between non-atomic ops and trigger-start

We protect the races of the concurrent state transitions between atomic PCM ops, but the checks between the non-atomic ops (hw_params, hw_free and prepare) and the atomic ops aren't perfect; there is a check of the conflicting PCM state at the beginning of hw_params & co, but the atomic PCM ops can be still issued during the non-atomic PCM operations.

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An example such scenario is that a thread A re-issues the PREPARE or HW_PARAMS for the already prepared stream, while another thread B triggers the PCM start in the middle of the prepare operation. Although this usually doesn't lead to much serious issues, it can give some inconsistency as reported by syzkaller (such as ODEBUG warning).

There are various atomic PCM ops, and basically the only problem is the PCM start as it operates from the PREPARED state. Other trigger commands (stop, etc) are for the running or the other special state, hence they are filtered as pre-condition.

This patch is for preventing the PCM trigger-start during the non- atomic operations in order to address the problems above. Fortunately, the hw_params, hw_free and prepare operations call snd_pcm_buffer_access_lock(), and this can be used for checking the concurrent operations at the PCM trigger -- which sets the runtime->buffer_accessing to a negative (if possible), so the PCM trigger just needs to check the runtime->buffer_accessing value; if it's negative, it means the concurrent non-atomic PCM ops is running.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.18%
Percentil entre todas las CVEs puntuadas: 6
Fecha de la puntuación: 4/10/2026

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).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation75 %
Impacto principalT1499.004 Application or System Exploitationimpact60 %
Impacto secundarioT1565.001 Stored Data Manipulationimpact50 %

AV:L + PR:L indica escalada local. La race condition entre ops no-atómicas y trigger-start en ALSA PCM puede causar DoS (ODEBUG warning, inconsistencia de estado) o corrupción de datos de audio mediante acceso concurrente al buffer.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Threat Intelligence Program Restrict File and Directory Permissions Remote Data Storage Filter Network Traffic Execution Prevention Encrypt Sensitive Information

Tecnologías afectadas (1)

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

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

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  "id": "CVE-2026-89979",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
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          "confidentialityImpact": "HIGH"
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  "published": "2026-09-16T11:17:08.770",
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  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: pcm: Fix race between non-atomic ops and trigger-start\n\nWe protect the races of the concurrent state transitions between\natomic PCM ops, but the checks between the non-atomic ops (hw_params,\nhw_free and prepare) and the atomic ops aren't perfect; there is a\ncheck of the conflicting PCM state at the beginning of hw_params & co,\nbut the atomic PCM ops can be still issued during the non-atomic PCM\noperations.  An example such scenario is that a thread A re-issues the\nPREPARE or HW_PARAMS for the already prepared stream, while another\nthread B triggers the PCM start in the middle of the prepare\noperation.  Although this usually doesn't lead to much serious issues,\nit can give some inconsistency as reported by syzkaller (such as\nODEBUG warning).\n\nThere are various atomic PCM ops, and basically the only problem is\nthe PCM start as it operates from the PREPARED state.  Other trigger\ncommands (stop, etc) are for the running or the other special state,\nhence they are filtered as pre-condition.\n\nThis patch is for preventing the PCM trigger-start during the non-\natomic operations in order to address the problems above.\nFortunately, the hw_params, hw_free and prepare operations call\nsnd_pcm_buffer_access_lock(), and this can be used for checking the\nconcurrent operations at the PCM trigger -- which sets the\nruntime->buffer_accessing to a negative (if possible), so the PCM\ntrigger just needs to check the runtime->buffer_accessing value; if\nit's negative, it means the concurrent non-atomic PCM ops is running."
    }
  ],
  "lastModified": "2026-09-17T10:17:05.353",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}