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CVE-2021-32707

Status: ModifiedMedium (4.3)—

Nextcloud Mail is a mail app for Nextcloud. In versions prior to 1.9.6, the Nextcloud Mail application does not, by default, render images in emails to not leak the read state. The privacy filter failed to filter images with a `background-image` CSS attribute. Note that the images were still passed through the Nextcloud image proxy, and thus there was no IP leakage. The issue was patched in version 1.9.6 and 1.10.0. No workarounds are known to exist.

CVSS

Exploitation probability (EPSS)

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)

Nextcloud — Mail

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2021-32707",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 4,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:S/C:N/I:P/A:N",
          "authentication": "SINGLE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "LOW",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 8,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 4.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "LOW"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 2.8
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
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          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
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          "vendor": "nextcloud",
          "product": "security-advisories",
          "versions": [
            {
              "status": "affected",
              "version": "< 1.9.6"
            }
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  ],
  "published": "2021-07-12T19:15:10.227",
  "references": [
    {
      "url": "https://github.com/nextcloud/mail/pull/5189",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xxp4-44xc-8crh",
      "tags": [
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      "source": "security-advisories@github.com"
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      "url": "https://hackerone.com/reports/1215251",
      "tags": [
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        "Third Party Advisory"
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      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/nextcloud/mail/pull/5189",
      "tags": [
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xxp4-44xc-8crh",
      "tags": [
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
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    {
      "url": "https://hackerone.com/reports/1215251",
      "tags": [
        "Exploit",
        "Third Party Advisory"
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-20"
        },
        {
          "lang": "en",
          "value": "CWE-200"
        }
      ]
    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-Other"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Nextcloud Mail is a mail app for Nextcloud. In versions prior to 1.9.6, the Nextcloud Mail application does not, by default, render images in emails to not leak the read state. The privacy filter failed to filter images with a `background-image` CSS attribute. Note that the images were still passed through the Nextcloud image proxy, and thus there was no IP leakage. The issue was patched in version 1.9.6 and 1.10.0. No workarounds are known to exist."
    },
    {
      "lang": "es",
      "value": "Nextcloud Mail es una aplicación de correo para Nextcloud. En versiones anteriores a 1.9.6, la aplicación Nextcloud Mail no renderiza, por defecto, las imágenes en los correos electrónicos para no filtrar el estado de lectura. El filtro de privacidad produce un fallo en filtrar las imágenes con un atributo CSS \"background-image\". Nótese que las imágenes seguían pasando mediante el proxy de imágenes de Nextcloud, y por lo tanto no había ningún filtrado de IP. El problema fue parcheado en versiones 1.9.6 y 1.10.0. No se conoce ninguna solución"
    }
  ],
  "lastModified": "2026-06-17T03:53:28.113",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:nextcloud:mail:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "3FB68076-7D5E-4E82-9BDD-548C92BD7447",
              "versionEndExcluding": "1.9.6"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "security-advisories@github.com"
}