CVE-2021-29631

Status: ModifiedHigh (7.8)—
In FreeBSD 13.0-STABLE before n246941-20f96f215562, 12.2-STABLE before r370400, 11.4-STABLE before r370399, 13.0-RELEASE before p4, 12.2-RELEASE before p10, and 11.4-RELEASE before p13, certain VirtIO-based device models in bhyve failed to handle errors when fetching I/O descriptors. A malicious guest may cause the device model to operate on uninitialized I/O vectors leading to memory corruption, crashing of the bhyve process, and possibly arbitrary code execution in the bhyve process.
CVSS

Version: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Base score: 7.8
Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.29%
Percentile among all scored CVEs: 19
Score date: 10/7/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)

Freebsd — Freebsd
CWEs

CWE-908
References

Raw JSON (NVD)

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{
  "id": "CVE-2021-29631",
  "cveTags": [],
  "metrics": {
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        "source": "nvd@nist.gov",
        "cvssData": {
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          "baseScore": 7.2,
          "accessVector": "LOCAL",
          "vectorString": "AV:L/AC:L/Au:N/C:C/I:C/A:C",
          "authentication": "NONE",
          "integrityImpact": "COMPLETE",
          "accessComplexity": "LOW",
          "availabilityImpact": "COMPLETE",
          "confidentialityImpact": "COMPLETE"
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        "acInsufInfo": false,
        "impactScore": 10,
        "baseSeverity": "HIGH",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 3.9,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
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          "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",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
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        "impactScore": 5.9,
        "exploitabilityScore": 1.8
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  "affected": [
    {
      "source": "secteam@freebsd.org",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "FreeBSD",
          "versions": [
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              "status": "affected",
              "version": "FreeBSD 13.0-RELEASE before p4, 12.2-RELEASE before p10, 11.4-RELEASE before p13"
            }
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  "published": "2021-08-30T18:15:08.923",
  "references": [
    {
      "url": "https://security.FreeBSD.org/advisories/FreeBSD-SA-21:13.bhyve.asc",
      "tags": [
        "Vendor Advisory"
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      "source": "secteam@freebsd.org"
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    {
      "url": "https://security.netapp.com/advisory/ntap-20210923-0004/",
      "tags": [
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  "vulnStatus": "Modified",
  "weaknesses": [
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      "description": [
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          "lang": "en",
          "value": "CWE-908"
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      "lang": "en",
      "value": "In FreeBSD 13.0-STABLE before n246941-20f96f215562, 12.2-STABLE before r370400, 11.4-STABLE before r370399, 13.0-RELEASE before p4, 12.2-RELEASE before p10, and 11.4-RELEASE before p13, certain VirtIO-based device models in bhyve failed to handle errors when fetching I/O descriptors. A malicious guest may cause the device model to operate on uninitialized I/O vectors leading to memory corruption, crashing of the bhyve process, and possibly arbitrary code execution in the bhyve process."
    },
    {
      "lang": "es",
      "value": "En FreeBSD versiones 13.0-STABLE anteriores a n246941-20f96f215562, 12.2-STABLE anteriores a r370400, 11.4-STABLE anteriores a r370399, 13.0-RELEASE anteriores a p4, 12.2-RELEASE anteriores a p10, y 11.4-RELEASE anteriores a p13, determinados modelos de dispositivos basados en VirtIO en bhyve presentaban un fallo al manejar los errores cuando se obtenían descriptores de E/S. Un huésped malicioso puede causar al modelo de dispositivo operar en vectores de E/S no inicializados, conllevando a una corrupción de la memoria, un bloqueo del proceso bhyve y, posiblemente, una ejecución de código arbitrario en el proceso bhyve."
    }
  ],
  "lastModified": "2026-06-17T03:48:03.800",
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