Vulnerability-Lookup

FKIE_CVE-2021-4221

Vulnerability from fkie_nvd - Published: 2022-12-22 20:15 - Updated: 2026-06-17 04:19

Severity

4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Summary

If a domain name contained a RTL character, it would cause the domain to be rendered to the right of the path. This could lead to user confusion and spoofing attacks. <br>*This bug only affects Firefox for Android. Other operating systems are unaffected.*<br>*Note*: Due to a clerical error this advisory was not included in the original announcement, and was added in Feburary 2022. This vulnerability affects Firefox < 92.

References

URL	Tags
security@mozilla.org	https://bugzilla.mozilla.org/show_bug.cgi?id=1704422	Exploit, Issue Tracking, Vendor Advisory
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2021-38/	Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://bugzilla.mozilla.org/show_bug.cgi?id=1704422	Exploit, Issue Tracking, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://www.mozilla.org/security/advisories/mfsa2021-38/	Vendor Advisory

Impacted products

	Vendor	Product	Version
	mozilla	firefox	*
	google	android	-

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "Firefox",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "92",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "security@mozilla.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "117CF1EF-253C-4D02-96C4-EA184FC46C3A",
              "versionEndExcluding": "92.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        },
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:google:android:-:*:*:*:*:*:*:*",
              "matchCriteriaId": "F8B9FEC8-73B6-43B8-B24E-1F7C20D91D26",
              "vulnerable": false
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ],
      "operator": "AND"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "If a domain name contained a RTL character, it would cause the domain to be rendered to the right of the path. This could lead to user confusion and spoofing attacks. \u003cbr\u003e*This bug only affects Firefox for Android. Other operating systems are unaffected.*\u003cbr\u003e*Note*: Due to a clerical error this advisory was not included in the original announcement, and was added in Feburary 2022. This vulnerability affects Firefox \u003c 92."
    },
    {
      "lang": "es",
      "value": "Si un nombre de dominio contuviera un car\u00e1cter RTL, el dominio se representar\u00eda a la derecha de la ruta. Esto podr\u00eda generar confusi\u00f3n en el usuario y ataques de suplantaci\u00f3n de identidad. \u003cbr\u003e*Este error s\u00f3lo afecta a Firefox para Android. Otros sistemas operativos no se ven afectados.*\u003cbr\u003e*Nota*: Debido a un error administrativo, este aviso no se incluy\u00f3 en el anuncio original y se agreg\u00f3 en febrero de 2022. Esta vulnerabilidad afecta a Firefox \u0026lt; 92."
    }
  ],
  "id": "CVE-2021-4221",
  "lastModified": "2026-06-17T04:19:14.537",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2021-4221",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2025-04-16T15:48:58.282021Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2022-12-22T20:15:12.337",
  "references": [
    {
      "source": "security@mozilla.org",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1704422"
    },
    {
      "source": "security@mozilla.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2021-38/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1704422"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2021-38/"
    }
  ],
  "sourceIdentifier": "security@mozilla.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-Other"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-1007"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}

CVE-2021-4221 (GCVE-0-2021-4221)

Vulnerability from cvelistv5 – Published: 2022-12-22 00:00 – Updated: 2025-04-16 15:49

Summary

Severity

4.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-04-16 15:48 UTC

CWE

Address bar spoofing on Firefox for Android due to RTL characters
CWE-1007 - Insufficient Visual Distinction of Homoglyphs Presented to User

Assigner

mozilla mitre root

References

2 references

URL	Tags
https://www.mozilla.org/security/advisories/mfsa2…
https://bugzilla.mozilla.org/show_bug.cgi?id=1704422

Impacted products

1 product

Vendor	Product	Version
Mozilla	Firefox	Affected: unspecified , < 92 (custom)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-03T17:16:04.358Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://www.mozilla.org/security/advisories/mfsa2021-38/"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1704422"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 4.3,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "NONE",
              "integrityImpact": "LOW",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "REQUIRED",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2021-4221",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-04-16T15:48:58.282021Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-1007",
                "description": "CWE-1007 Insufficient Visual Distinction of Homoglyphs Presented to User",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-04-16T15:49:45.732Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "Firefox",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "92",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "If a domain name contained a RTL character, it would cause the domain to be rendered to the right of the path. This could lead to user confusion and spoofing attacks. \u003cbr\u003e*This bug only affects Firefox for Android. Other operating systems are unaffected.*\u003cbr\u003e*Note*: Due to a clerical error this advisory was not included in the original announcement, and was added in Feburary 2022. This vulnerability affects Firefox \u003c 92."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "Address bar spoofing on Firefox for Android due to RTL characters",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2022-12-22T00:00:00.000Z",
        "orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
        "shortName": "mozilla"
      },
      "references": [
        {
          "url": "https://www.mozilla.org/security/advisories/mfsa2021-38/"
        },
        {
          "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1704422"
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
    "assignerShortName": "mozilla",
    "cveId": "CVE-2021-4221",
    "datePublished": "2022-12-22T00:00:00.000Z",
    "dateReserved": "2022-02-18T00:00:00.000Z",
    "dateUpdated": "2025-04-16T15:49:45.732Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.