Vulnerability-Lookup

FKIE_CVE-2020-26950

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

Severity

8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Summary

In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition. This vulnerability affects Firefox < 82.0.3, Firefox ESR < 78.4.1, and Thunderbird < 78.4.2.

References

URL	Tags
security@mozilla.org	http://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.html	Exploit, Third Party Advisory, VDB Entry
security@mozilla.org	https://bugzilla.mozilla.org/show_bug.cgi?id=1675905	Exploit, Issue Tracking, Vendor Advisory
security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2020-49/	Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	http://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.html	Exploit, Third Party Advisory, VDB Entry
af854a3a-2127-422b-91ae-364da2661108	https://bugzilla.mozilla.org/show_bug.cgi?id=1675905	Exploit, Issue Tracking, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://www.mozilla.org/security/advisories/mfsa2020-49/	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 82.0.3"
            }
          ]
        },
        {
          "product": "Firefox ESR",
          "vendor": "Mozilla",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 78.4.1"
            }
          ]
        },
        {
          "product": "Thunderbird",
          "vendor": "Mozilla",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 78.4.2"
            }
          ]
        }
      ],
      "source": "security@mozilla.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "7F743C78-6F4E-4BD7-A878-B887A2C42BDC",
              "versionEndExcluding": "82.0.3",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "08D6779A-1193-446D-AE3E-D859D539A170",
              "versionEndExcluding": "78.4.1",
              "vulnerable": true
            },
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              "matchCriteriaId": "635C87C4-E16B-4320-A339-45C8E1DF0401",
              "versionEndExcluding": "78.4.2",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition. This vulnerability affects Firefox \u003c 82.0.3, Firefox ESR \u003c 78.4.1, and Thunderbird \u003c 78.4.2."
    },
    {
      "lang": "es",
      "value": "En determinadas circunstancias, el opcode MCallGetProperty puede ser emitido con suposiciones no cumplidas, resultando en una condici\u00f3n de uso de la memoria previamente liberada explotable. Esta vulnerabilidad afecta a Firefox versiones anteriores a 82.0.3, Firefox ESR versiones anteriores a 78.4.1, y Thunderbird versiones anteriores a 78.4.2"
    }
  ],
  "id": "CVE-2020-26950",
  "lastModified": "2026-06-17T03:08:36.207",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "HIGH",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "COMPLETE",
          "baseScore": 9.3,
          "confidentialityImpact": "COMPLETE",
          "integrityImpact": "COMPLETE",
          "vectorString": "AV:N/AC:M/Au:N/C:C/I:C/A:C",
          "version": "2.0"
        },
        "exploitabilityScore": 8.6,
        "impactScore": 10.0,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2020-12-09T01:15:12.503",
  "references": [
    {
      "source": "security@mozilla.org",
      "tags": [
        "Exploit",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "url": "http://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.html"
    },
    {
      "source": "security@mozilla.org",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1675905"
    },
    {
      "source": "security@mozilla.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2020-49/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Exploit",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "url": "http://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.html"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Vendor Advisory"
      ],
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1675905"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.mozilla.org/security/advisories/mfsa2020-49/"
    }
  ],
  "sourceIdentifier": "security@mozilla.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2020-26950 (GCVE-0-2020-26950)

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

Summary

Severity

No CVSS data available.

CWE

Write side effects in MCallGetProperty opcode not accounted for

Assigner

mozilla mitre root

References

3 references

URL	Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1675905	x_refsource_MISC
https://www.mozilla.org/security/advisories/mfsa2…	x_refsource_CONFIRM
http://packetstormsecurity.com/files/166175/Firef…	x_refsource_MISC

Impacted products

3 products

Vendor	Product	Version
Mozilla	Firefox	Affected: < 82.0.3
Mozilla	Firefox ESR	Affected: < 78.4.1
Mozilla	Thunderbird	Affected: < 78.4.2

Show details on NVD website

JSON

To clipboard

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          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "Firefox",
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            {
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        {
          "product": "Thunderbird",
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              "version": "\u003c 78.4.2"
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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.

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.