{
  "cveId": "CVE-2021-23960",
  "url": "https://patchblox.com/security/cve/CVE-2021-23960",
  "summary": "CVE-2021-23960 is fixed in 11 products on 2 platforms, first by firefox 85.0\u002Bbuild1-0ubuntu0.18.04.1, released January 25, 2021. It is not reported as exploited. Patch Radar priority: High.",
  "title": "Firefox ESR and 2 others: Performing garbage collection on re-declared JavaScript variables resulted in a user-after-poison, and\u2026",
  "description": "Performing garbage collection on re-declared JavaScript variables resulted in a user-after-poison, and a potentially exploitable crash. This vulnerability affects Firefox \u003C 85, Thunderbird \u003C 78.7, and Firefox ESR \u003C 78.7.",
  "published": "2021-01-25T16:00:00Z",
  "severity": "Important",
  "cvss": 8.8,
  "epss": 0.01289,
  "epssPercentile": 0.70382,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://nvd.nist.gov/vuln/detail/CVE-2021-23960",
  "fixes": [
    {
      "platform": "windows-app",
      "product": "Mozilla Firefox ESR (en-US)",
      "fixedVersion": "91.0",
      "fix": "Mozilla Firefox ESR (en-US) 91.0",
      "url": "https://patchblox.com/security/fix/windows-app/mozilla.firefox.esr-91.0",
      "released": "2021-08-04T00:00:00Z"
    },
    {
      "platform": "windows-app",
      "product": "Mozilla Thunderbird (en-US)",
      "fixedVersion": "78.10.0",
      "fix": "Mozilla Thunderbird (en-US) 78.10.0",
      "url": "https://patchblox.com/security/fix/windows-app/mozilla.thunderbird-78.10.0",
      "released": "2021-04-15T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "firefox",
      "release": "RHEL 8",
      "fixedVersion": "0:78.7.0-2.el8_3",
      "fix": "RHSA-2021:0288",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2021-0288",
      "released": "2021-01-27T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "firefox",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "85.0\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "firefox 85.0\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-firefox-85.0-build1-0ubuntu0.18.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "firefox",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "85.0\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "firefox 85.0\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-firefox-85.0-build1-0ubuntu0.20.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "firefox",
      "release": "ol 8",
      "fixedVersion": "0:78.7.0-2.0.1.el8_3",
      "fix": "ELSA-2021-0288",
      "url": "https://patchblox.com/security/fix/linux/elsa-2021-0288",
      "released": "2021-01-28T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "firefox-geckodriver",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "85.0\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "firefox-geckodriver 85.0\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-firefox-geckodriver-85.0-build1-0ubuntu0.18.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "firefox-geckodriver",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "85.0\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "firefox-geckodriver 85.0\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-firefox-geckodriver-85.0-build1-0ubuntu0.20.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "firefox-mozsymbols",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "85.0\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "firefox-mozsymbols 85.0\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-firefox-mozsymbols-85.0-build1-0ubuntu0.18.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "firefox-mozsymbols",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "85.0\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "firefox-mozsymbols 85.0\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-firefox-mozsymbols-85.0-build1-0ubuntu0.20.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "RHEL 8",
      "fixedVersion": "0:78.7.0-1.el8_3",
      "fix": "RHSA-2021:0298",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2021-0298",
      "released": "2021-01-28T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "thunderbird 1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-thunderbird-1-78.8.1-build1-0ubuntu0.18.04.1",
      "released": "2021-04-22T07:54:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "thunderbird 1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-thunderbird-1-78.7.1-build1-0ubuntu0.20.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "ol 8",
      "fixedVersion": "0:78.7.0-1.0.1.el8_3",
      "fix": "ELSA-2021-0298",
      "url": "https://patchblox.com/security/fix/linux/elsa-2021-0298",
      "released": "2021-01-29T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-gnome-support",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "thunderbird-gnome-support 1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-thunderbird-gnome-support-1-78.8.1-build1-0ubuntu0.18.04.1",
      "released": "2021-04-22T07:54:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-gnome-support",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "thunderbird-gnome-support 1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-thunderbird-gnome-support-1-78.7.1-build1-0ubuntu0.20.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-mozsymbols",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "thunderbird-mozsymbols 1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-thunderbird-mozsymbols-1-78.8.1-build1-0ubuntu0.18.04.1",
      "released": "2021-04-22T07:54:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-mozsymbols",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "thunderbird-mozsymbols 1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-thunderbird-mozsymbols-1-78.7.1-build1-0ubuntu0.20.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-calendar-timezones",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "xul-ext-calendar-timezones 1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-xul-ext-calendar-timezones-1-78.8.1-build1-0ubuntu0.18.04.1",
      "released": "2021-04-22T07:54:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-calendar-timezones",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "xul-ext-calendar-timezones 1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-xul-ext-calendar-timezones-1-78.7.1-build1-0ubuntu0.20.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-gdata-provider",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "xul-ext-gdata-provider 1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-xul-ext-gdata-provider-1-78.8.1-build1-0ubuntu0.18.04.1",
      "released": "2021-04-22T07:54:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-gdata-provider",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "xul-ext-gdata-provider 1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-xul-ext-gdata-provider-1-78.7.1-build1-0ubuntu0.20.04.1",
      "released": "2021-01-25T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-lightning",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "xul-ext-lightning 1:78.8.1\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-xul-ext-lightning-1-78.8.1-build1-0ubuntu0.18.04.1",
      "released": "2021-04-22T07:54:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-lightning",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "xul-ext-lightning 1:78.7.1\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-xul-ext-lightning-1-78.7.1-build1-0ubuntu0.20.04.1",
      "released": "2021-01-25T16:00:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}