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CVE-2021-4251

Status: ModifiedMedium (6.1)—
Severity6.1Medium · CVSS 3.1
Exploitation probability0.42 %higher than 35% of CVEs
Active exploitationNonot in the CISA catalog
Public exploitNot knownno public code found

A vulnerability classified as problematic was found in as. This vulnerability affects the function getFullURL of the file include.cdn.php. The manipulation leads to cross site scripting. The attack can be initiated remotely. The name of the patch is 4acad1e3d2c34c017473ceea442fb3e3e078b2bd. It is recommended to apply a patch to fix this issue. The identifier of this vulnerability is VDB-216208.

CVSS

Base score
6.1
Version
3.1
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days
0.42 %
Percentile among all scored CVEs
35
Score date
10/21/2026

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)

AS Project — AS

CWEs

References

Show 4 references

Raw JSON (NVD)

Show
{
  "id": "CVE-2021-4251",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2021-4251",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2025-04-14T17:02:19.042675Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "cna@vuldb.com",
        "cvssData": {
          "scope": "UNCHANGED",
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          "attackVector": "NETWORK",
          "baseSeverity": "LOW",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 2.1
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
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          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "REQUIRED",
          "attackComplexity": "LOW",
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          "confidentialityImpact": "LOW"
        },
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        "exploitabilityScore": 2.8
      }
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  },
  "affected": [
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      "affectedData": [
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          "vendor": "unspecified",
          "product": "as",
          "versions": [
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              "version": "n/a"
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    }
  ],
  "published": "2022-12-18T22:15:10.167",
  "references": [
    {
      "url": "https://github.com/andrewsauder/as/commit/4acad1e3d2c34c017473ceea442fb3e3e078b2bd",
      "tags": [
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        "Third Party Advisory"
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      "source": "cna@vuldb.com"
    },
    {
      "url": "https://vuldb.com/?id.216208",
      "tags": [
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      ],
      "source": "cna@vuldb.com"
    },
    {
      "url": "https://github.com/andrewsauder/as/commit/4acad1e3d2c34c017473ceea442fb3e3e078b2bd",
      "tags": [
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        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://vuldb.com/?id.216208",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "cna@vuldb.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-707"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "A vulnerability classified as problematic was found in as. This vulnerability affects the function getFullURL of the file include.cdn.php. The manipulation leads to cross site scripting. The attack can be initiated remotely. The name of the patch is 4acad1e3d2c34c017473ceea442fb3e3e078b2bd. It is recommended to apply a patch to fix this issue. The identifier of this vulnerability is VDB-216208."
    },
    {
      "lang": "es",
      "value": "Una vulnerabilidad fue encontrada en as y clasificada como problemática. Esta vulnerabilidad afecta a la función getFullURL del archivo include.cdn.php. La manipulación conduce a Cross-Site Scripting. El ataque se puede iniciar de forma remota. El nombre del parche es 4acad1e3d2c34c017473ceea442fb3e3e078b2bd. Se recomienda aplicar un parche para solucionar este problema. El identificador de esta vulnerabilidad es VDB-216208."
    }
  ],
  "lastModified": "2026-06-17T04:19:21.310",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:as_project:as:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "F248945C-5520-4F03-9245-2DA75C60C18A",
              "versionEndExcluding": "2021-11-03"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cna@vuldb.com"
}