{
  "cveId": "CVE-2021-23961",
  "url": "https://patchblox.com/security/cve/CVE-2021-23961",
  "summary": "CVE-2021-23961 is fixed in 10 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 1 other: Further techniques that built on the slipstream research combined with a malicious webpage could have\u2026",
  "description": "Further techniques that built on the slipstream research combined with a malicious webpage could have exposed both an internal network\u0027s hosts as well as services running on the user\u0027s local machine. This vulnerability affects Firefox \u003C 85.",
  "published": "2021-01-25T16:00:00Z",
  "severity": "Important",
  "cvss": 7.4,
  "epss": 0.01477,
  "epssPercentile": 0.74063,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://nvd.nist.gov/vuln/detail/CVE-2021-23961",
  "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": "linux",
      "product": "firefox",
      "release": "RHEL 8",
      "fixedVersion": "0:78.10.0-1.el8_3",
      "fix": "RHSA-2021:1360",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2021-1360",
      "released": "2021-04-26T00:00:00Z"
    },
    {
      "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": "0:78.10.0-1.0.1.el8_3",
      "fix": "ELSA-2021-1360",
      "url": "https://patchblox.com/security/fix/linux/elsa-2021-1360",
      "released": "2021-04-27T00:00:00Z"
    },
    {
      "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": "0:78.10.0-1.el8_3",
      "fix": "RHSA-2021:1353",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2021-1353",
      "released": "2021-04-26T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "fix": "thunderbird 1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-thunderbird-1-78.11.0-build1-0ubuntu0.18.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "fix": "thunderbird 1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-thunderbird-1-78.11.0-build1-0ubuntu0.20.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "ol 8",
      "fixedVersion": "0:78.10.0-1.0.1.el8_3",
      "fix": "ELSA-2021-1353",
      "url": "https://patchblox.com/security/fix/linux/elsa-2021-1353",
      "released": "2021-04-27T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-gnome-support",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "fix": "thunderbird-gnome-support 1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-thunderbird-gnome-support-1-78.11.0-build1-0ubuntu0.18.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-gnome-support",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "fix": "thunderbird-gnome-support 1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-thunderbird-gnome-support-1-78.11.0-build1-0ubuntu0.20.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-mozsymbols",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "fix": "thunderbird-mozsymbols 1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-thunderbird-mozsymbols-1-78.11.0-build1-0ubuntu0.18.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-mozsymbols",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "fix": "thunderbird-mozsymbols 1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-thunderbird-mozsymbols-1-78.11.0-build1-0ubuntu0.20.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-calendar-timezones",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "fix": "xul-ext-calendar-timezones 1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-xul-ext-calendar-timezones-1-78.11.0-build1-0ubuntu0.18.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-calendar-timezones",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "fix": "xul-ext-calendar-timezones 1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-xul-ext-calendar-timezones-1-78.11.0-build1-0ubuntu0.20.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-gdata-provider",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "fix": "xul-ext-gdata-provider 1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-xul-ext-gdata-provider-1-78.11.0-build1-0ubuntu0.18.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-gdata-provider",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "fix": "xul-ext-gdata-provider 1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-xul-ext-gdata-provider-1-78.11.0-build1-0ubuntu0.20.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-lightning",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "fix": "xul-ext-lightning 1:78.11.0\u002Bbuild1-0ubuntu0.18.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-xul-ext-lightning-1-78.11.0-build1-0ubuntu0.18.04.2",
      "released": "2021-06-01T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-lightning",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "fix": "xul-ext-lightning 1:78.11.0\u002Bbuild1-0ubuntu0.20.04.2",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-xul-ext-lightning-1-78.11.0-build1-0ubuntu0.20.04.2",
      "released": "2021-06-01T17:00:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-10T13:56:55Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}