Vulnerability-Lookup

FKIE_CVE-2020-26951

Vulnerability from fkie_nvd - Published: 2020-12-09 01:15 - Updated: 2026-06-17 03:08

Severity

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

Summary

A parsing and event loading mismatch in Firefox's SVG code could have allowed load events to fire, even after sanitization. An attacker already capable of exploiting an XSS vulnerability in privileged internal pages could have used this attack to bypass our built-in sanitizer. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

References

URL	Tags
security@mozilla.org	https://bugzilla.mozilla.org/show_bug.cgi?id=1667113	Issue Tracking, Permissions Required, Vendor Advisory
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2020-50/	Vendor Advisory
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2020-51/	Vendor Advisory
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2020-52/	Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://bugzilla.mozilla.org/show_bug.cgi?id=1667113	Issue Tracking, Permissions Required, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://www.mozilla.org/security/advisories/mfsa2020-50/	Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://www.mozilla.org/security/advisories/mfsa2020-51/	Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://www.mozilla.org/security/advisories/mfsa2020-52/	Vendor Advisory

Impacted products

Vendor	Product	Version
mozilla	firefox	*
mozilla	firefox_esr	*
mozilla	thunderbird	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "Firefox",
          "vendor": "Mozilla",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 83"
            }
          ]
        },
        {
          "product": "Firefox ESR",
          "vendor": "Mozilla",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 78.5"
            }
          ]
        },
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 78.5"
            }
          ]
        }
      ],
      "source": "security@mozilla.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "9385C808-43DD-4D02-B1A9-89A2E3986DF2",
              "versionEndExcluding": "83.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "36160ED9-05B8-4E38-8C67-49EE1738AF8B",
              "versionEndExcluding": "78.5",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "C169EC17-3490-437D-A36B-40C3DE316175",
              "versionEndExcluding": "78.5",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A parsing and event loading mismatch in Firefox\u0027s SVG code could have allowed load events to fire, even after sanitization. An attacker already capable of exploiting an XSS vulnerability in privileged internal pages could have used this attack to bypass our built-in sanitizer. This vulnerability affects Firefox \u003c 83, Firefox ESR \u003c 78.5, and Thunderbird \u003c 78.5."
    },
    {
      "lang": "es",
      "value": "Un desajuste en el an\u00e1lisis y la carga de eventos en el c\u00f3digo SVG de Firefox podr\u00eda haber permitido a unos eventos de carga dispararse, incluso despu\u00e9s del saneamiento. Un atacante ya capaz de explotar una vulnerabilidad de tipo XSS en p\u00e1ginas internas privilegiadas podr\u00eda haber usado este ataque para omitir nuestro sanitizador incorporado. Esta vulnerabilidad afecta a Firefox versiones anteriores a 83, Firefox ESR versiones anteriores a  78.5, y Thunderbird versiones anteriores a 78.5"
    }
  ],
  "id": "CVE-2020-26951",
  "lastModified": "2026-06-17T03:08:36.320",
  "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": 6.1,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
          "version": "3.1"
        },
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        "impactScore": 2.7,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2020-12-09T01:15:12.643",
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      "tags": [
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        "Permissions Required",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1667113"
    },
    {
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      "tags": [
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    },
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      "tags": [
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    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Issue Tracking",
        "Permissions Required",
        "Vendor Advisory"
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      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1667113"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2020-50/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2020-51/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2020-52/"
    }
  ],
  "sourceIdentifier": "security@mozilla.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2020-26951 (GCVE-0-2020-26951)

Vulnerability from cvelistv5 – Published: 2020-12-09 00:19 – Updated: 2024-08-04 16:03

Summary

Severity

No CVSS data available.

CWE

Parsing mismatches could confuse and bypass security sanitizer for chrome privileged code

Assigner

mozilla CNA under the mitre root

CNA scorecard E 38/100 over 545 records in the last 180 days details

References

4 references

URL	Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1667113	x_refsource_MISC
https://www.mozilla.org/security/advisories/mfsa2…	x_refsource_CONFIRM
https://www.mozilla.org/security/advisories/mfsa2…	x_refsource_CONFIRM
https://www.mozilla.org/security/advisories/mfsa2…	x_refsource_CONFIRM

Impacted products

3 products

Vendor	Product	Version
Mozilla	Firefox	Affected: < 83
Mozilla	Firefox ESR	Affected: < 78.5
Mozilla	Thunderbird	Affected: < 78.5

Show details on NVD website

JSON

To clipboard

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          },
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            ],
            "url": "https://www.mozilla.org/security/advisories/mfsa2020-51/"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
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          "vendor": "Mozilla",
          "versions": [
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          ]
        },
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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

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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.

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