{
  "cveId": "CVE-2021-4126",
  "url": "https://patchblox.com/security/cve/CVE-2021-4126",
  "summary": "CVE-2021-4126 is fixed in 7 products on 2 platforms, first by Mozilla Thunderbird (en-US) 91.4.1, released December 16, 2021. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "Mozilla Thunderbird and 1 other: When receiving an OpenPGP/MIME signed email message that contains an additional outer MIME message layer,\u2026",
  "description": "When receiving an OpenPGP/MIME signed email message that contains an additional outer MIME message layer, for example a message footer added by a mailing list gateway, Thunderbird only considered the inner signed message for the signature validity. This gave the false impression that the additional contents were also covered by the digital signature. Starting with Thunderbird version 91.4.1, only the signature that belongs to the top level MIME part will be considered for the displayed status. This vulnerability affects Thunderbird \u003C 91.4.1.",
  "published": "2021-12-23T16:00:00Z",
  "severity": "medium",
  "cvss": 6.5,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N",
  "epss": 0.00461,
  "epssPercentile": 0.40191,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://nvd.nist.gov/vuln/detail/CVE-2021-4126",
  "fixes": [
    {
      "platform": "windows-app",
      "product": "Mozilla Thunderbird (en-US)",
      "fixedVersion": "91.4.1",
      "fix": "Mozilla Thunderbird (en-US) 91.4.1",
      "url": "https://patchblox.com/security/fix/windows-app/mozilla.thunderbird-91.4.1",
      "released": "2021-12-16T00:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "1:91.4.1-1",
      "fix": "DEBIAN-CVE-2021-4126",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-4126",
      "released": "2022-12-22T20:15:11Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "1:91.4.1-1",
      "fix": "DEBIAN-CVE-2021-4126",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-4126",
      "released": "2022-12-22T20:15:11Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Debian 14",
      "fixedVersion": "1:91.4.1-1",
      "fix": "DEBIAN-CVE-2021-4126",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-4126",
      "released": "2022-12-22T20:15:11Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "thunderbird 1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-thunderbird-1-91.5.0-build1-0ubuntu0.18.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "thunderbird 1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-thunderbird-1-91.5.0-build1-0ubuntu0.20.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu1",
      "fix": "thunderbird 1:91.5.0\u002Bbuild1-0ubuntu1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-thunderbird-1-91.5.0-build1-0ubuntu1",
      "released": "2022-01-12T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-gnome-support",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "thunderbird-gnome-support 1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-thunderbird-gnome-support-1-91.5.0-build1-0ubuntu0.18.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-gnome-support",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "thunderbird-gnome-support 1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-thunderbird-gnome-support-1-91.5.0-build1-0ubuntu0.20.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-gnome-support",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu1",
      "fix": "thunderbird-gnome-support 1:91.5.0\u002Bbuild1-0ubuntu1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-thunderbird-gnome-support-1-91.5.0-build1-0ubuntu1",
      "released": "2022-01-12T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-mozsymbols",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "thunderbird-mozsymbols 1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-thunderbird-mozsymbols-1-91.5.0-build1-0ubuntu0.18.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-mozsymbols",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "thunderbird-mozsymbols 1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-thunderbird-mozsymbols-1-91.5.0-build1-0ubuntu0.20.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "thunderbird-mozsymbols",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu1",
      "fix": "thunderbird-mozsymbols 1:91.5.0\u002Bbuild1-0ubuntu1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-thunderbird-mozsymbols-1-91.5.0-build1-0ubuntu1",
      "released": "2022-01-12T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-calendar-timezones",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "xul-ext-calendar-timezones 1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-xul-ext-calendar-timezones-1-91.5.0-build1-0ubuntu0.18.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-calendar-timezones",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "xul-ext-calendar-timezones 1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-xul-ext-calendar-timezones-1-91.5.0-build1-0ubuntu0.20.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-calendar-timezones",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu1",
      "fix": "xul-ext-calendar-timezones 1:91.5.0\u002Bbuild1-0ubuntu1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-xul-ext-calendar-timezones-1-91.5.0-build1-0ubuntu1",
      "released": "2022-01-12T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-gdata-provider",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "xul-ext-gdata-provider 1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-xul-ext-gdata-provider-1-91.5.0-build1-0ubuntu0.18.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-gdata-provider",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "xul-ext-gdata-provider 1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-xul-ext-gdata-provider-1-91.5.0-build1-0ubuntu0.20.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-gdata-provider",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu1",
      "fix": "xul-ext-gdata-provider 1:91.5.0\u002Bbuild1-0ubuntu1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-xul-ext-gdata-provider-1-91.5.0-build1-0ubuntu1",
      "released": "2022-01-12T16:00:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-lightning",
      "release": "Ubuntu 18.04.6 LTS (bionic)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "fix": "xul-ext-lightning 1:91.5.0\u002Bbuild1-0ubuntu0.18.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-bionic-xul-ext-lightning-1-91.5.0-build1-0ubuntu0.18.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-lightning",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "fix": "xul-ext-lightning 1:91.5.0\u002Bbuild1-0ubuntu0.20.04.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-xul-ext-lightning-1-91.5.0-build1-0ubuntu0.20.04.1",
      "released": "2023-02-16T14:15:00Z"
    },
    {
      "platform": "linux",
      "product": "xul-ext-lightning",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "1:91.5.0\u002Bbuild1-0ubuntu1",
      "fix": "xul-ext-lightning 1:91.5.0\u002Bbuild1-0ubuntu1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-xul-ext-lightning-1-91.5.0-build1-0ubuntu1",
      "released": "2022-01-12T16:00:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}