CVE catalog

CVE-2017-7820

UBUNTU-

[CVE catalog]

The "instanceof" operator can bypass the Xray wrapper mechanism. When called on web content from the browser itself or an extension the web content can provide its own result for that operator, possibly tricking the browser or extension into mishandling the element. This vulnerability affects Firefox < 56.

Severity
Medium · CVSS 5.3CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Published
Updated
Source
[NVD] · [CVE record]
EPSS
1.16% · Oct 27, 2026

Reported versions and fixes

Each observation applies to its named package, distribution, and release. Distribution backports can fix a vulnerability while retaining an older upstream version number.

Distribution / releasePackageVersionStatusSource
Ubuntu18.04firefox56.0+build6-0ubuntu1Fixed[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox56.0+build6-0ubuntu0.16.04.1Fixed[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox56.0+build6-0ubuntu0.14.04.1Fixed[UBUNTU-CVE-2017-7820]

Showing 3 fix observations. All 90 observations, including unknown and conflicting reports, are available below.

Provider details and historical evidence
Distribution / releasePackageVersionStatusSource
Ubuntu14.04firefox24.0+build1-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox25.0+build3-0ubuntu0.13.10.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox28.0+build1-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox28.0+build2-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox28.0+build2-0ubuntu2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox28.0~b2+build1-0ubuntu2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox29.0+build1-0ubuntu0.14.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox30.0+build1-0ubuntu0.14.04.3Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox31.0+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox32.0+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox32.0.3+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox33.0+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox34.0+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox35.0+build3-0ubuntu0.14.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox35.0.1+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox36.0+build2-0ubuntu0.14.04.4Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox36.0.1+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox36.0.4+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox37.0+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox37.0.1+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox37.0.2+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox38.0+build3-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox39.0+build5-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox39.0.3+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox40.0+build4-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox40.0+build4-0ubuntu0.14.04.4Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox40.0.3+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox41.0+build3-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox41.0.1+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox41.0.2+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox42.0+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox43.0+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox43.0.4+build3-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox44.0+build3-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox44.0.1+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox44.0.2+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox45.0+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox45.0.1+build1-0ubuntu0.14.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox45.0.2+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox46.0+build5-0ubuntu0.14.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox46.0.1+build1-0ubuntu0.14.04.3Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox47.0+build3-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox48.0+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox49.0+build4-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox49.0.2+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox50.0+build2-0ubuntu0.14.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox50.0.2+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox50.1.0+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox51.0.1+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox51.0.1+build2-0ubuntu0.14.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox52.0+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox52.0.1+build2-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox52.0.2+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox53.0+build6-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox53.0.2+build1-0ubuntu0.14.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox53.0.3+build1-0ubuntu0.14.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox54.0+build3-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox55.0.1+build2-0ubuntu0.14.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox55.0.2+build1-0ubuntu0.14.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu14.04firefox56.0+build6-0ubuntu0.14.04.1Fixed[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox41.0.2+build2-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox42.0+build2-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox44.0+build3-0ubuntu2Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox44.0.1+build1-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox44.0.2+build1-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox45.0+build2-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox45.0.1+build1-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox45.0.2+build1-0ubuntu1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox46.0+build5-0ubuntu0.16.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox46.0.1+build1-0ubuntu0.16.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox47.0+build3-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox48.0+build2-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox49.0+build4-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox49.0.2+build2-0ubuntu0.16.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox50.0+build2-0ubuntu0.16.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox50.0.2+build1-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox50.1.0+build2-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox51.0.1+build2-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox51.0.1+build2-0ubuntu0.16.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox52.0+build2-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox52.0.1+build2-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox52.0.2+build1-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox53.0+build6-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox53.0.2+build1-0ubuntu0.16.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox53.0.3+build1-0ubuntu0.16.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox54.0+build3-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox55.0.1+build2-0ubuntu0.16.04.2Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox55.0.2+build1-0ubuntu0.16.04.1Affected[UBUNTU-CVE-2017-7820]
Ubuntu16.04firefox56.0+build6-0ubuntu0.16.04.1Fixed[UBUNTU-CVE-2017-7820]
Ubuntu18.04firefox56.0+build6-0ubuntu1Fixed[UBUNTU-CVE-2017-7820]
Original provider fields
{
  "package_releases": [],
  "fixed_versions": [],
  "distribution_packages": [
    {
      "name": "firefox",
      "distro": "ubuntu",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "56.0+build6-0ubuntu0.14.04.1"
            }
          ]
        }
      ],
      "release": "14.04",
      "versions": [
        "24.0+build1-0ubuntu1",
        "25.0+build3-0ubuntu0.13.10.1",
        "28.0~b2+build1-0ubuntu2",
        "28.0+build1-0ubuntu1",
        "28.0+build2-0ubuntu1",
        "28.0+build2-0ubuntu2",
        "29.0+build1-0ubuntu0.14.04.2",
        "30.0+build1-0ubuntu0.14.04.3",
        "31.0+build1-0ubuntu0.14.04.1",
        "32.0+build1-0ubuntu0.14.04.1",
        "32.0.3+build1-0ubuntu0.14.04.1",
        "33.0+build2-0ubuntu0.14.04.1",
        "34.0+build2-0ubuntu0.14.04.1",
        "35.0+build3-0ubuntu0.14.04.2",
        "35.0.1+build1-0ubuntu0.14.04.1",
        "36.0+build2-0ubuntu0.14.04.4",
        "36.0.1+build2-0ubuntu0.14.04.1",
        "36.0.4+build1-0ubuntu0.14.04.1",
        "37.0+build2-0ubuntu0.14.04.1",
        "37.0.1+build1-0ubuntu0.14.04.1",
        "37.0.2+build1-0ubuntu0.14.04.1",
        "38.0+build3-0ubuntu0.14.04.1",
        "39.0+build5-0ubuntu0.14.04.1",
        "39.0.3+build2-0ubuntu0.14.04.1",
        "40.0+build4-0ubuntu0.14.04.1",
        "40.0+build4-0ubuntu0.14.04.4",
        "40.0.3+build1-0ubuntu0.14.04.1",
        "41.0+build3-0ubuntu0.14.04.1",
        "41.0.1+build2-0ubuntu0.14.04.1",
        "41.0.2+build2-0ubuntu0.14.04.1",
        "42.0+build2-0ubuntu0.14.04.1",
        "43.0+build1-0ubuntu0.14.04.1",
        "43.0.4+build3-0ubuntu0.14.04.1",
        "44.0+build3-0ubuntu0.14.04.1",
        "44.0.1+build2-0ubuntu0.14.04.1",
        "44.0.2+build1-0ubuntu0.14.04.1",
        "45.0+build2-0ubuntu0.14.04.1",
        "45.0.1+build1-0ubuntu0.14.04.2",
        "45.0.2+build1-0ubuntu0.14.04.1",
        "46.0+build5-0ubuntu0.14.04.2",
        "46.0.1+build1-0ubuntu0.14.04.3",
        "47.0+build3-0ubuntu0.14.04.1",
        "48.0+build2-0ubuntu0.14.04.1",
        "49.0+build4-0ubuntu0.14.04.1",
        "49.0.2+build2-0ubuntu0.14.04.1",
        "50.0+build2-0ubuntu0.14.04.2",
        "50.0.2+build1-0ubuntu0.14.04.1",
        "50.1.0+build2-0ubuntu0.14.04.1",
        "51.0.1+build2-0ubuntu0.14.04.1",
        "51.0.1+build2-0ubuntu0.14.04.2",
        "52.0+build2-0ubuntu0.14.04.1",
        "52.0.1+build2-0ubuntu0.14.04.1",
        "52.0.2+build1-0ubuntu0.14.04.1",
        "53.0+build6-0ubuntu0.14.04.1",
        "53.0.2+build1-0ubuntu0.14.04.2",
        "53.0.3+build1-0ubuntu0.14.04.2",
        "54.0+build3-0ubuntu0.14.04.1",
        "55.0.1+build2-0ubuntu0.14.04.2",
        "55.0.2+build1-0ubuntu0.14.04.1"
      ],
      "ecosystem": "deb",
      "provider_url": "https://osv.dev/vulnerability/UBUNTU-CVE-2017-7820",
      "fixed_version": "56.0+build6-0ubuntu0.14.04.1",
      "provider_source": "pypi",
      "provider_record_id": "UBUNTU-CVE-2017-7820",
      "provider_updated_at": "2026-04-22T11:33:00.821594Z"
    },
    {
      "name": "firefox",
      "distro": "ubuntu",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "56.0+build6-0ubuntu0.16.04.1"
            }
          ]
        }
      ],
      "release": "16.04",
      "versions": [
        "41.0.2+build2-0ubuntu1",
        "42.0+build2-0ubuntu1",
        "44.0+build3-0ubuntu2",
        "44.0.1+build1-0ubuntu1",
        "44.0.2+build1-0ubuntu1",
        "45.0+build2-0ubuntu1",
        "45.0.1+build1-0ubuntu1",
        "45.0.2+build1-0ubuntu1",
        "46.0+build5-0ubuntu0.16.04.2",
        "46.0.1+build1-0ubuntu0.16.04.2",
        "47.0+build3-0ubuntu0.16.04.1",
        "48.0+build2-0ubuntu0.16.04.1",
        "49.0+build4-0ubuntu0.16.04.1",
        "49.0.2+build2-0ubuntu0.16.04.2",
        "50.0+build2-0ubuntu0.16.04.2",
        "50.0.2+build1-0ubuntu0.16.04.1",
        "50.1.0+build2-0ubuntu0.16.04.1",
        "51.0.1+build2-0ubuntu0.16.04.1",
        "51.0.1+build2-0ubuntu0.16.04.2",
        "52.0+build2-0ubuntu0.16.04.1",
        "52.0.1+build2-0ubuntu0.16.04.1",
        "52.0.2+build1-0ubuntu0.16.04.1",
        "53.0+build6-0ubuntu0.16.04.1",
        "53.0.2+build1-0ubuntu0.16.04.2",
        "53.0.3+build1-0ubuntu0.16.04.2",
        "54.0+build3-0ubuntu0.16.04.1",
        "55.0.1+build2-0ubuntu0.16.04.2",
        "55.0.2+build1-0ubuntu0.16.04.1"
      ],
      "ecosystem": "deb",
      "provider_url": "https://osv.dev/vulnerability/UBUNTU-CVE-2017-7820",
      "fixed_version": "56.0+build6-0ubuntu0.16.04.1",
      "provider_source": "pypi",
      "provider_record_id": "UBUNTU-CVE-2017-7820",
      "provider_updated_at": "2026-04-22T11:33:00.821594Z"
    },
    {
      "name": "firefox",
      "distro": "ubuntu",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "56.0+build6-0ubuntu1"
            }
          ]
        }
      ],
      "release": "18.04",
      "versions": [],
      "ecosystem": "deb",
      "provider_url": "https://osv.dev/vulnerability/UBUNTU-CVE-2017-7820",
      "fixed_version": "56.0+build6-0ubuntu1",
      "provider_source": "pypi",
      "provider_record_id": "UBUNTU-CVE-2017-7820",
      "provider_updated_at": "2026-04-22T11:33:00.821594Z"
    }
  ]
}

OpenFactory catalog packages

Matching against OpenFactory catalog package versions is in progress.

Observed:

References

[FIRST EPSS] · [OSV Package Vulnerability Database] · [SUSE security advisories and VEX]