Vulnerability-Lookup

FKIE_CVE-2021-23991

Vulnerability from fkie_nvd - Published: 2021-06-24 14:15 - Updated: 2026-06-17 03:39

Severity

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

Summary

If a Thunderbird user has previously imported Alice's OpenPGP key, and Alice has extended the validity period of her key, but Alice's updated key has not yet been imported, an attacker may send an email containing a crafted version of Alice's key with an invalid subkey, Thunderbird might subsequently attempt to use the invalid subkey, and will fail to send encrypted email to Alice. This vulnerability affects Thunderbird < 78.9.1.

References

URL	Tags
security@mozilla.org	https://bugzilla.mozilla.org/show_bug.cgi?id=1673240	Exploit, Issue Tracking, Vendor Advisory
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2021-13/	Release Notes, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://bugzilla.mozilla.org/show_bug.cgi?id=1673240	Exploit, Issue Tracking, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://www.mozilla.org/security/advisories/mfsa2021-13/	Release Notes, Vendor Advisory

Impacted products

	Vendor	Product	Version
	mozilla	thunderbird	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "78.9.1",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "security@mozilla.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "717003F7-C1B4-4A52-A10F-13DB37ED1FCE",
              "versionEndExcluding": "78.9.1",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "If a Thunderbird user has previously imported Alice\u0027s OpenPGP key, and Alice has extended the validity period of her key, but Alice\u0027s updated key has not yet been imported, an attacker may send an email containing a crafted version of Alice\u0027s key with an invalid subkey, Thunderbird might subsequently attempt to use the invalid subkey, and will fail to send encrypted email to Alice. This vulnerability affects Thunderbird \u003c 78.9.1."
    },
    {
      "lang": "es",
      "value": "Si un usuario de Thunderbird ha importado previamente la clave OpenPGP de Alice, y Alice ha ampliado el periodo de validez de su clave, pero la clave actualizada de Alice a\u00fan no ha sido importada, un atacante puede enviar un correo electr\u00f3nico conteniendo una versi\u00f3n dise\u00f1ada de la clave de Alice con una subclave no v\u00e1lida, Thunderbird podr\u00eda posteriormente intentar usar la subclave no v\u00e1lida, y producir\u00e1 un fallo al enviar el correo electr\u00f3nico cifrado a Alice. Esta vulnerabilidad afecta a Thunderbird versiones anteriores a 78.9.1"
    }
  ],
  "id": "CVE-2021-23991",
  "lastModified": "2026-06-17T03:39:07.293",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "HIGH",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "NONE",
          "baseScore": 4.0,
          "confidentialityImpact": "PARTIAL",
          "integrityImpact": "PARTIAL",
          "vectorString": "AV:N/AC:H/Au:N/C:P/I:P/A:N",
          "version": "2.0"
        },
        "exploitabilityScore": 4.9,
        "impactScore": 4.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.8,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 5.2,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-06-24T14:15:09.197",
  "references": [
    {
      "source": "security@mozilla.org",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1673240"
    },
    {
      "source": "security@mozilla.org",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2021-13/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1673240"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2021-13/"
    }
  ],
  "sourceIdentifier": "security@mozilla.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-Other"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2021-23991 (GCVE-0-2021-23991)

Vulnerability from cvelistv5 – Published: 2021-06-24 13:27 – Updated: 2024-08-03 19:14

Summary

Severity

No CVSS data available.

CWE

An attacker may use Thunderbird's OpenPGP key refresh mechanism to poison an existing key

Assigner

mozilla CNA under the mitre root

CNA scorecard E 38/100 over 679 records in the last 180 days details

References

2 references

URL	Tags
https://www.mozilla.org/security/advisories/mfsa2…	x_refsource_MISC
https://bugzilla.mozilla.org/show_bug.cgi?id=1673240	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
Mozilla	Thunderbird	Affected: unspecified , < 78.9.1 (custom)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-03T19:14:10.003Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://www.mozilla.org/security/advisories/mfsa2021-13/"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1673240"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThan": "78.9.1",
              "status": "affected",
              "version": "unspecified",
              "versionType": "custom"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "If a Thunderbird user has previously imported Alice\u0027s OpenPGP key, and Alice has extended the validity period of her key, but Alice\u0027s updated key has not yet been imported, an attacker may send an email containing a crafted version of Alice\u0027s key with an invalid subkey, Thunderbird might subsequently attempt to use the invalid subkey, and will fail to send encrypted email to Alice. This vulnerability affects Thunderbird \u003c 78.9.1."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "An attacker may use Thunderbird\u0027s OpenPGP key refresh mechanism to poison an existing key",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2021-06-24T13:27:10.000Z",
        "orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
        "shortName": "mozilla"
      },
      "references": [
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://www.mozilla.org/security/advisories/mfsa2021-13/"
        },
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1673240"
        }
      ],
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "security@mozilla.org",
          "ID": "CVE-2021-23991",
          "STATE": "PUBLIC"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "Thunderbird",
                      "version": {
                        "version_data": [
                          {
                            "version_affected": "\u003c",
                            "version_value": "78.9.1"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "Mozilla"
              }
            ]
          }
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "eng",
              "value": "If a Thunderbird user has previously imported Alice\u0027s OpenPGP key, and Alice has extended the validity period of her key, but Alice\u0027s updated key has not yet been imported, an attacker may send an email containing a crafted version of Alice\u0027s key with an invalid subkey, Thunderbird might subsequently attempt to use the invalid subkey, and will fail to send encrypted email to Alice. This vulnerability affects Thunderbird \u003c 78.9.1."
            }
          ]
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "An attacker may use Thunderbird\u0027s OpenPGP key refresh mechanism to poison an existing key"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "https://www.mozilla.org/security/advisories/mfsa2021-13/",
              "refsource": "MISC",
              "url": "https://www.mozilla.org/security/advisories/mfsa2021-13/"
            },
            {
              "name": "https://bugzilla.mozilla.org/show_bug.cgi?id=1673240",
              "refsource": "MISC",
              "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1673240"
            }
          ]
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe",
    "assignerShortName": "mozilla",
    "cveId": "CVE-2021-23991",
    "datePublished": "2021-06-24T13:27:10.000Z",
    "dateReserved": "2021-01-13T00:00:00.000Z",
    "dateUpdated": "2024-08-03T19:14:10.003Z",
    "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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

Loading timeline…

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.

Action not permitted