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CVE-2021-21705 (GCVE-0-2021-21705)

Vulnerability from cvelistv5 – Published: 2021-10-04 04:00 – Updated: 2024-09-17 04:09
VLAI
Title
Incorrect URL validation in FILTER_VALIDATE_URL
Summary
In PHP versions 7.3.x below 7.3.29, 7.4.x below 7.4.21 and 8.0.x below 8.0.8, when using URL validation functionality via filter_var() function with FILTER_VALIDATE_URL parameter, an URL with invalid password field can be accepted as valid. This can lead to the code incorrectly parsing the URL and potentially leading to other security implications - like contacting a wrong server or making a wrong access decision.
Severity
4.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
CWE
  • CWE-20 - Improper Input Validation
Assigner
References
Impacted products
Vendor Product Version CPE status
PHP Group PHP Affected: 7.3.x , < 7.3.29 (custom)
Affected: 7.4.x , < 7.4.21 (custom)
Affected: 8.0.X , < 8.0.8 (custom)
guessed Create a notification for this product.
Date Public
2021-06-28 00:00
Credits
reported by vi at hackberry dot xyz
Show details on NVD website
To clipboard 

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                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 1.4,
              "source": "security@php.net",
              "type": "Secondary"
            },
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 5.3,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "LOW",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 3.9,
              "impactScore": 1.4,
              "source": "nvd@nist.gov",
              "type": "Primary"
            }
          ]
        },
        "published": "2021-10-04T04:15:08.210",
        "references": [
          {
            "source": "security@php.net",
            "tags": [
              "Exploit",
              "Issue Tracking",
              "Patch",
              "Vendor Advisory"
            ],
            "url": "https://bugs.php.net/bug.php?id=81122"
          },
          {
            "source": "security@php.net",
            "tags": [
              "Third Party Advisory"
            ],
            "url": "https://security.gentoo.org/glsa/202209-20"
          },
          {
            "source": "security@php.net",
            "tags": [
              "Third Party Advisory"
            ],
            "url": "https://security.netapp.com/advisory/ntap-20211029-0006/"
          },
          {
            "source": "security@php.net",
            "tags": [
              "Patch",
              "Vendor Advisory"
            ],
            "url": "https://www.oracle.com/security-alerts/cpujan2022.html"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Exploit",
              "Issue Tracking",
              "Patch",
              "Vendor Advisory"
            ],
            "url": "https://bugs.php.net/bug.php?id=81122"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Third Party Advisory"
            ],
            "url": "https://security.gentoo.org/glsa/202209-20"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Third Party Advisory"
            ],
            "url": "https://security.netapp.com/advisory/ntap-20211029-0006/"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Patch",
              "Vendor Advisory"
            ],
            "url": "https://www.oracle.com/security-alerts/cpujan2022.html"
          }
        ],
        "sourceIdentifier": "security@php.net",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-20"
              }
            ],
            "source": "security@php.net",
            "type": "Secondary"
          },
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-20"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-28T07:43:21+00:00",
      "cve": "CVE-2021-21705",
      "id": "CVE-2021-21705",
      "initial_release_date": "2021-07-01T00:00:00+00:00",
      "product_status:fixed": "514",
      "product_status:known_affected": "101",
      "product_status:known_not_affected": "26",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "php: SSRF bypass in FILTER_VALIDATE_URL",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-21705.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-13T00:03:59Z",
      "cve": "CVE-2021-21705",
      "id": "CVE-2021-21705",
      "initial_release_date": "2023-02-15T03:46:10Z",
      "product_status:known_affected": "1273",
      "product_status:known_not_affected": "673",
      "product_status:recommended": "4133",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2021-21705",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2021-21705.json",
      "version": "16"
    }
  }
}



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Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.