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CVE-2021-4321

Status: ModifiedMedium (4.3)—

Policy bypass in Blink in Google Chrome prior to 91.0.4472.77 allowed a remote attacker to bypass content security policy via a crafted HTML page. (Chromium security severity: Low)

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)

Google — Chrome

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2021-4321",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 4.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "chrome-cve-admin@google.com",
      "affectedData": [
        {
          "vendor": "Google",
          "product": "Chrome",
          "versions": [
            {
              "status": "affected",
              "version": "91.0.4472.77",
              "lessThan": "91.0.4472.77",
              "versionType": "custom"
            }
          ]
        }
      ]
    }
  ],
  "published": "2023-07-29T00:15:10.553",
  "references": [
    {
      "url": "https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "source": "chrome-cve-admin@google.com"
    },
    {
      "url": "https://crbug.com/1161891",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "source": "chrome-cve-admin@google.com"
    },
    {
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PQKT7EGDD2P3L7S3NXEDDRCPK4NNZNWJ/",
      "source": "chrome-cve-admin@google.com"
    },
    {
      "url": "https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://crbug.com/1161891",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PQKT7EGDD2P3L7S3NXEDDRCPK4NNZNWJ/",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Policy bypass in Blink in Google Chrome prior to 91.0.4472.77 allowed a remote attacker to bypass content security policy via a crafted HTML page. (Chromium security severity: Low)"
    }
  ],
  "lastModified": "2026-06-17T04:19:30.103",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "E013E0FE-A60A-4C98-91CA-F5D06FD43116",
              "versionEndExcluding": "91.0.4472.77"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "chrome-cve-admin@google.com"
}