GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2021-43528 (GCVE-0-2021-43528)

Vulnerability from cvelistv5 – Published: 2021-12-08 21:21 – Updated: 2024-08-04 03:55
VLAI
Summary
Thunderbird unexpectedly enabled JavaScript in the composition area. The JavaScript execution context was limited to this area and did not receive chrome-level privileges, but could be used as a stepping stone to further an attack with other vulnerabilities. This vulnerability affects Thunderbird < 91.4.0.
Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
CWE
  • JavaScript unexpectedly enabled for the composition area
Assigner
References
Impacted products
Vendor Product Version CPE status
Mozilla Thunderbird Affected: unspecified , < 91.4.0 (custom)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-04T03:55:29.399Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://www.mozilla.org/security/advisories/mfsa2021-54/"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1742579"
          },
          {
            "name": "DSA-5034",
            "tags": [
              "vendor-advisory",
              "x_refsource_DEBIAN",
              "x_transferred"
            ],
            "url": "https://www.debian.org/security/2022/dsa-5034"
          },
          {
            "name": "[debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update",
            "tags": [
              "mailing-list",
              "x_refsource_MLIST",
              "x_transferred"
            ],
            "url": "https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html"
          },
          {
            "name": "GLSA-202208-14",
            "tags": [
              "vendor-advisory",
              "x_refsource_GENTOO",
              "x_transferred"
            ],
            "url": "https://security.gentoo.org/glsa/202208-14"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "91.4.0",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Thunderbird unexpectedly enabled JavaScript in the composition area. The JavaScript execution context was limited to this area and did not receive chrome-level privileges, but could be used as a stepping stone to further an attack with other vulnerabilities. This vulnerability affects Thunderbird \u003c 91.4.0."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "JavaScript unexpectedly enabled for the composition area",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2022-08-10T05:12:51.000Z",
        "orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
        "shortName": "mozilla"
      },
      "references": [
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://www.mozilla.org/security/advisories/mfsa2021-54/"
        },
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1742579"
        },
        {
          "name": "DSA-5034",
          "tags": [
            "vendor-advisory",
            "x_refsource_DEBIAN"
          ],
          "url": "https://www.debian.org/security/2022/dsa-5034"
        },
        {
          "name": "[debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update",
          "tags": [
            "mailing-list",
            "x_refsource_MLIST"
          ],
          "url": "https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html"
        },
        {
          "name": "GLSA-202208-14",
          "tags": [
            "vendor-advisory",
            "x_refsource_GENTOO"
          ],
          "url": "https://security.gentoo.org/glsa/202208-14"
        }
      ],
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "security@mozilla.org",
          "ID": "CVE-2021-43528",
          "STATE": "PUBLIC"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "Thunderbird",
                      "version": {
                        "version_data": [
                          {
                            "version_affected": "\u003c",
                            "version_value": "91.4.0"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "Mozilla"
              }
            ]
          }
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "eng",
              "value": "Thunderbird unexpectedly enabled JavaScript in the composition area. The JavaScript execution context was limited to this area and did not receive chrome-level privileges, but could be used as a stepping stone to further an attack with other vulnerabilities. This vulnerability affects Thunderbird \u003c 91.4.0."
            }
          ]
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "JavaScript unexpectedly enabled for the composition area"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "https://www.mozilla.org/security/advisories/mfsa2021-54/",
              "refsource": "MISC",
              "url": "https://www.mozilla.org/security/advisories/mfsa2021-54/"
            },
            {
              "name": "https://bugzilla.mozilla.org/show_bug.cgi?id=1742579",
              "refsource": "MISC",
              "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1742579"
            },
            {
              "name": "DSA-5034",
              "refsource": "DEBIAN",
              "url": "https://www.debian.org/security/2022/dsa-5034"
            },
            {
              "name": "[debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update",
              "refsource": "MLIST",
              "url": "https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html"
            },
            {
              "name": "GLSA-202208-14",
              "refsource": "GENTOO",
              "url": "https://security.gentoo.org/glsa/202208-14"
            }
          ]
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
    "assignerShortName": "mozilla",
    "cveId": "CVE-2021-43528",
    "datePublished": "2021-12-08T21:21:12.000Z",
    "dateReserved": "2021-11-08T00:00:00.000Z",
    "dateUpdated": "2024-08-04T03:55:29.399Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2021-43528",
      "date": "2026-09-20",
      "epss": "0.01267",
      "percentile": "0.68452"
    },
    "fkie_nvd": {
      "configurations": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*",
                  "matchCriteriaId": "6F0BE95D-5BE5-49F7-92BA-CF3A3920D447",
                  "versionEndExcluding": "91.4.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        },
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*",
                  "matchCriteriaId": "DEECE5FC-CACF-4496-A3E7-164736409252",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*",
                  "matchCriteriaId": "07B237A9-69A3-4A9C-9DA0-4E06BD37AE73",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*",
                  "matchCriteriaId": "FA6FEEC2-9F11-4643-8827-749718254FED",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Thunderbird unexpectedly enabled JavaScript in the composition area. The JavaScript execution context was limited to this area and did not receive chrome-level privileges, but could be used as a stepping stone to further an attack with other vulnerabilities. This vulnerability affects Thunderbird \u003c 91.4.0."
        },
        {
          "lang": "es",
          "value": "Thunderbird habilit\u00f3 inesperadamente JavaScript en el \u00e1rea de composici\u00f3n. El contexto de ejecuci\u00f3n de JavaScript se limitaba a esta \u00e1rea y no recib\u00eda privilegios a nivel de cromo, pero pod\u00eda ser usado como un trampol\u00edn para avanzar en un ataque con otras vulnerabilidades. Esta vulnerabilidad afecta a Thunderbird versiones anteriores a 91.4.0"
        }
      ],
      "id": "CVE-2021-43528",
      "lastModified": "2024-11-21T06:29:21.643",
      "metrics": {
        "cvssMetricV2": [
          {
            "acInsufInfo": false,
            "baseSeverity": "MEDIUM",
            "cvssData": {
              "accessComplexity": "MEDIUM",
              "accessVector": "NETWORK",
              "authentication": "NONE",
              "availabilityImpact": "NONE",
              "baseScore": 4.3,
              "confidentialityImpact": "NONE",
              "integrityImpact": "PARTIAL",
              "vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
              "version": "2.0"
            },
            "exploitabilityScore": 8.6,
            "impactScore": 2.9,
            "obtainAllPrivilege": false,
            "obtainOtherPrivilege": false,
            "obtainUserPrivilege": false,
            "source": "nvd@nist.gov",
            "type": "Primary",
            "userInteractionRequired": true
          }
        ],
        "cvssMetricV31": [
          {
            "cvssData": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 6.5,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "NONE",
              "integrityImpact": "HIGH",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "REQUIRED",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
              "version": "3.1"
            },
            "exploitabilityScore": 2.8,
            "impactScore": 3.6,
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      },
      "published": "2021-12-08T22:15:09.210",
      "references": [
        {
          "source": "security@mozilla.org",
          "tags": [
            "Broken Link",
            "Issue Tracking",
            "Permissions Required",
            "Vendor Advisory"
          ],
          "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1742579"
        },
        {
          "source": "security@mozilla.org",
          "tags": [
            "Mailing List",
            "Third Party Advisory"
          ],
          "url": "https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html"
        },
        {
          "source": "security@mozilla.org",
          "tags": [
            "Third Party Advisory"
          ],
          "url": "https://security.gentoo.org/glsa/202208-14"
        },
        {
          "source": "security@mozilla.org",
          "tags": [
            "Issue Tracking",
            "Third Party Advisory"
          ],
          "url": "https://www.debian.org/security/2022/dsa-5034"
        },
        {
          "source": "security@mozilla.org",
          "tags": [
            "Vendor Advisory"
          ],
          "url": "https://www.mozilla.org/security/advisories/mfsa2021-54/"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "tags": [
            "Broken Link",
            "Issue Tracking",
            "Permissions Required",
            "Vendor Advisory"
          ],
          "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1742579"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "tags": [
            "Mailing List",
            "Third Party Advisory"
          ],
          "url": "https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "tags": [
            "Third Party Advisory"
          ],
          "url": "https://security.gentoo.org/glsa/202208-14"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "tags": [
            "Issue Tracking",
            "Third Party Advisory"
          ],
          "url": "https://www.debian.org/security/2022/dsa-5034"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "tags": [
            "Vendor Advisory"
          ],
          "url": "https://www.mozilla.org/security/advisories/mfsa2021-54/"
        }
      ],
      "sourceIdentifier": "security@mozilla.org",
      "vulnStatus": "Modified",
      "weaknesses": [
        {
          "description": [
            {
              "lang": "en",
              "value": "CWE-269"
            }
          ],
          "source": "nvd@nist.gov",
          "type": "Primary"
        }
      ]
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "Thunderbird",
                "vendor": "Mozilla",
                "versions": [
                  {
                    "lessThan": "91.4.0",
                    "status": "affected",
                    "version": "unspecified",
                    "versionType": "custom"
                  }
                ]
              }
            ],
            "source": "security@mozilla.org"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "6F0BE95D-5BE5-49F7-92BA-CF3A3920D447",
                    "versionEndExcluding": "91.4.0",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          },
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*",
                    "matchCriteriaId": "DEECE5FC-CACF-4496-A3E7-164736409252",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*",
                    "matchCriteriaId": "07B237A9-69A3-4A9C-9DA0-4E06BD37AE73",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*",
                    "matchCriteriaId": "FA6FEEC2-9F11-4643-8827-749718254FED",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Thunderbird unexpectedly enabled JavaScript in the composition area. The JavaScript execution context was limited to this area and did not receive chrome-level privileges, but could be used as a stepping stone to further an attack with other vulnerabilities. This vulnerability affects Thunderbird \u003c 91.4.0."
          },
          {
            "lang": "es",
            "value": "Thunderbird habilit\u00f3 inesperadamente JavaScript en el \u00e1rea de composici\u00f3n. El contexto de ejecuci\u00f3n de JavaScript se limitaba a esta \u00e1rea y no recib\u00eda privilegios a nivel de cromo, pero pod\u00eda ser usado como un trampol\u00edn para avanzar en un ataque con otras vulnerabilidades. Esta vulnerabilidad afecta a Thunderbird versiones anteriores a 91.4.0"
          }
        ],
        "id": "CVE-2021-43528",
        "lastModified": "2026-06-17T04:11:04.370",
        "metrics": {
          "cvssMetricV2": [
            {
              "acInsufInfo": false,
              "baseSeverity": "MEDIUM",
              "cvssData": {
                "accessComplexity": "MEDIUM",
                "accessVector": "NETWORK",
                "authentication": "NONE",
                "availabilityImpact": "NONE",
                "baseScore": 4.3,
                "confidentialityImpact": "NONE",
                "integrityImpact": "PARTIAL",
                "vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
                "version": "2.0"
              },
              "exploitabilityScore": 8.6,
              "impactScore": 2.9,
              "obtainAllPrivilege": false,
              "obtainOtherPrivilege": false,
              "obtainUserPrivilege": false,
              "source": "nvd@nist.gov",
              "type": "Primary",
              "userInteractionRequired": true
            }
          ],
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 6.5,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "REQUIRED",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 3.6,
              "source": "nvd@nist.gov",
              "type": "Primary"
            }
          ]
        },
        "published": "2021-12-08T22:15:09.210",
        "references": [
          {
            "source": "security@mozilla.org",
            "tags": [
              "Broken Link",
              "Issue Tracking",
              "Permissions Required",
              "Vendor Advisory"
            ],
            "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1742579"
          },
          {
            "source": "security@mozilla.org",
            "tags": [
              "Mailing List",
              "Third Party Advisory"
            ],
            "url": "https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html"
          },
          {
            "source": "security@mozilla.org",
            "tags": [
              "Third Party Advisory"
            ],
            "url": "https://security.gentoo.org/glsa/202208-14"
          },
          {
            "source": "security@mozilla.org",
            "tags": [
              "Issue Tracking",
              "Third Party Advisory"
            ],
            "url": "https://www.debian.org/security/2022/dsa-5034"
          },
          {
            "source": "security@mozilla.org",
            "tags": [
              "Vendor Advisory"
            ],
            "url": "https://www.mozilla.org/security/advisories/mfsa2021-54/"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Broken Link",
              "Issue Tracking",
              "Permissions Required",
              "Vendor Advisory"
            ],
            "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1742579"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Mailing List",
              "Third Party Advisory"
            ],
            "url": "https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Third Party Advisory"
            ],
            "url": "https://security.gentoo.org/glsa/202208-14"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Issue Tracking",
              "Third Party Advisory"
            ],
            "url": "https://www.debian.org/security/2022/dsa-5034"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Vendor Advisory"
            ],
            "url": "https://www.mozilla.org/security/advisories/mfsa2021-54/"
          }
        ],
        "sourceIdentifier": "security@mozilla.org",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-269"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2025-11-21T15:34:05+00:00",
      "cve": "CVE-2021-43528",
      "id": "CVE-2021-43528",
      "initial_release_date": "2021-12-07T00:00:00+00:00",
      "product_status:fixed": "58",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "Mozilla: JavaScript unexpectedly enabled for the composition area",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-43528.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2025-09-07T00:01:32Z",
      "cve": "CVE-2021-43528",
      "id": "CVE-2021-43528",
      "initial_release_date": "2023-02-15T03:36:57Z",
      "product_status:known_affected": "1",
      "product_status:recommended": "106",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2021-43528",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2021-43528.json",
      "version": "17"
    }
  }
}



Log in or create an account to share your comment.




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.