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CVE-2021-26933

Estado: ModificadaMedia (5.5)—

Se detectó un problema en Xen versiones 4.9 hasta 4.14.x. En Arm, un invitado puede controlar si los accesos a la memoria pasan por encima de la caché. Esto significa que Xen necesita asegurarse de que todas las escrituras (como las que se producen durante el scrubbing) han llegado a la memoria antes de entregar la página a un invitado. Desgraciadamente, la operación de limpieza de la caché se realiza antes de comprobar si la página ha sido limpiada. Por lo tanto, no existe garantía de que todas las escrituras lleguen a la memoria

CVSS

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 (3)

Debian — Debian LinuxFedoraproject — FedoraXEN — XEN

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2021-26933",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 2.1,
          "accessVector": "LOCAL",
          "vectorString": "AV:L/AC:L/Au:N/C:P/I:N/A:N",
          "authentication": "NONE",
          "integrityImpact": "NONE",
          "accessComplexity": "LOW",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "LOW",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 3.9,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
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        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
      }
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  },
  "affected": [
    {
      "source": "cve@mitre.org",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
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  "published": "2021-02-17T02:15:13.097",
  "references": [
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      "url": "http://xenbits.xen.org/xsa/advisory-364.html",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "source": "cve@mitre.org"
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      "source": "cve@mitre.org"
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      "tags": [
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      "source": "cve@mitre.org"
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
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      "tags": [
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
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  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "An issue was discovered in Xen 4.9 through 4.14.x. On Arm, a guest is allowed to control whether memory accesses are bypassing the cache. This means that Xen needs to ensure that all writes (such as the ones during scrubbing) have reached the memory before handing over the page to a guest. Unfortunately, the operation to clean the cache is happening before checking if the page was scrubbed. Therefore there is no guarantee when all the writes will reach the memory."
    },
    {
      "lang": "es",
      "value": "Se detectó un problema en Xen versiones 4.9 hasta 4.14.x. En Arm, un invitado puede controlar si los accesos a la memoria pasan por encima de la caché. Esto significa que Xen necesita asegurarse de que todas las escrituras (como las que se producen durante el scrubbing) han llegado a la memoria antes de entregar la página a un invitado. Desgraciadamente, la operación de limpieza de la caché se realiza antes de comprobar si la página ha sido limpiada. Por lo tanto, no existe garantía de que todas las escrituras lleguen a la memoria"
    }
  ],
  "lastModified": "2026-06-17T03:44:02.227",
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}