# CVE-2020-12406: Firefox ESR: Mozilla Developer Iain Ireland discovered a missing type check during unboxed objects removal, resulting… CVE-2020-12406 is fixed in 10 products on 2 platforms, first by firefox 77.0.1+build1-0ubuntu0.18.04.1, released June 2, 2020. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2020-12406 - Priority: High - CVSS: 8.8 (Important) - EPSS: 0.0102 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Jun 1, 2020 - Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2020-12406 ## Description Mozilla Developer Iain Ireland discovered a missing type check during unboxed objects removal, resulting in a crash. We presume that with enough effort that it could be exploited to run arbitrary code. This vulnerability affects Thunderbird < 68.9.0, Firefox < 77, and Firefox ESR < 68.9. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Windows apps | Mozilla Firefox ESR (en-US) | 78.0esr | [Mozilla Firefox ESR (en-US) 78.0esr](https://patchblox.com/security/data/fix/windows-app/mozilla.firefox.esr-78.0esr.md) | Jun 25, 2020 | | Linux | firefox RHEL 8 | 0:68.9.0-1.el8_2 | [RHSA-2020:2379](https://patchblox.com/security/data/fix/linux/rhsa-2020-2379.md) | Jun 3, 2020 | | Linux | firefox Ubuntu 18.04.6 LTS (bionic) | 77.0.1+build1-0ubuntu0.18.04.1 | [firefox 77.0.1+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-77.0.1-build1-0ubuntu0.18.04.1.md) | Jun 2, 2020 | | Linux | firefox Ubuntu 20.04 LTS (focal) | 77.0.1+build1-0ubuntu0.20.04.1 | [firefox 77.0.1+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-77.0.1-build1-0ubuntu0.20.04.1.md) | Jun 2, 2020 | | Linux | firefox ol 8 | 0:68.9.0-1.0.1.el8_2 | [ELSA-2020-2379](https://patchblox.com/security/data/fix/linux/elsa-2020-2379.md) | Jun 5, 2020 | | Linux | firefox-geckodriver Ubuntu 18.04.6 LTS (bionic) | 77.0.1+build1-0ubuntu0.18.04.1 | [firefox-geckodriver 77.0.1+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-geckodriver-77.0.1-build1-0ubuntu0.18.04.1.md) | Jun 2, 2020 | | Linux | firefox-geckodriver Ubuntu 20.04 LTS (focal) | 77.0.1+build1-0ubuntu0.20.04.1 | [firefox-geckodriver 77.0.1+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-geckodriver-77.0.1-build1-0ubuntu0.20.04.1.md) | Jun 2, 2020 | | Linux | firefox-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 77.0.1+build1-0ubuntu0.18.04.1 | [firefox-mozsymbols 77.0.1+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-mozsymbols-77.0.1-build1-0ubuntu0.18.04.1.md) | Jun 2, 2020 | | Linux | firefox-mozsymbols Ubuntu 20.04 LTS (focal) | 77.0.1+build1-0ubuntu0.20.04.1 | [firefox-mozsymbols 77.0.1+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-mozsymbols-77.0.1-build1-0ubuntu0.20.04.1.md) | Jun 2, 2020 | | Linux | thunderbird RHEL 8 | 0:68.9.0-1.el8_2 | [RHSA-2020:2614](https://patchblox.com/security/data/fix/linux/rhsa-2020-2614.md) | Jun 22, 2020 | | Linux | thunderbird Ubuntu 18.04.6 LTS (bionic) | 1:68.10.0+build1-0ubuntu0.18.04.1 | [thunderbird 1:68.10.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-1-68.10.0-build1-0ubuntu0.18.04.1.md) | Oct 8, 2020 | | Linux | thunderbird Ubuntu 20.04 LTS (focal) | 1:68.10.0+build1-0ubuntu0.20.04.1 | [thunderbird 1:68.10.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-1-68.10.0-build1-0ubuntu0.20.04.1.md) | Oct 8, 2020 | | Linux | thunderbird ol 8 | 0:68.9.0-1.0.1.el8_2 | [ELSA-2020-2614](https://patchblox.com/security/data/fix/linux/elsa-2020-2614.md) | Jun 23, 2020 | | Linux | thunderbird-gnome-support Ubuntu 18.04.6 LTS (bionic) | 1:68.10.0+build1-0ubuntu0.18.04.1 | [thunderbird-gnome-support 1:68.10.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-gnome-support-1-68.10.0-build1-0ubuntu0.18.04.1.md) | Oct 8, 2020 | | Linux | thunderbird-gnome-support Ubuntu 20.04 LTS (focal) | 1:68.10.0+build1-0ubuntu0.20.04.1 | [thunderbird-gnome-support 1:68.10.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-gnome-support-1-68.10.0-build1-0ubuntu0.20.04.1.md) | Oct 8, 2020 | | Linux | thunderbird-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 1:68.10.0+build1-0ubuntu0.18.04.1 | [thunderbird-mozsymbols 1:68.10.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-mozsymbols-1-68.10.0-build1-0ubuntu0.18.04.1.md) | Oct 8, 2020 | | Linux | thunderbird-mozsymbols Ubuntu 20.04 LTS (focal) | 1:68.10.0+build1-0ubuntu0.20.04.1 | [thunderbird-mozsymbols 1:68.10.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-mozsymbols-1-68.10.0-build1-0ubuntu0.20.04.1.md) | Oct 8, 2020 | | Linux | xul-ext-calendar-timezones Ubuntu 18.04.6 LTS (bionic) | 1:68.10.0+build1-0ubuntu0.18.04.1 | [xul-ext-calendar-timezones 1:68.10.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-calendar-timezones-1-68.10.0-build1-0ubuntu0.18.04.1.md) | Oct 8, 2020 | | Linux | xul-ext-calendar-timezones Ubuntu 20.04 LTS (focal) | 1:68.10.0+build1-0ubuntu0.20.04.1 | [xul-ext-calendar-timezones 1:68.10.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-calendar-timezones-1-68.10.0-build1-0ubuntu0.20.04.1.md) | Oct 8, 2020 | | Linux | xul-ext-gdata-provider Ubuntu 18.04.6 LTS (bionic) | 1:68.10.0+build1-0ubuntu0.18.04.1 | [xul-ext-gdata-provider 1:68.10.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-gdata-provider-1-68.10.0-build1-0ubuntu0.18.04.1.md) | Oct 8, 2020 | | Linux | xul-ext-gdata-provider Ubuntu 20.04 LTS (focal) | 1:68.10.0+build1-0ubuntu0.20.04.1 | [xul-ext-gdata-provider 1:68.10.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-gdata-provider-1-68.10.0-build1-0ubuntu0.20.04.1.md) | Oct 8, 2020 | | Linux | xul-ext-lightning Ubuntu 18.04.6 LTS (bionic) | 1:68.10.0+build1-0ubuntu0.18.04.1 | [xul-ext-lightning 1:68.10.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-lightning-1-68.10.0-build1-0ubuntu0.18.04.1.md) | Oct 8, 2020 | | Linux | xul-ext-lightning Ubuntu 20.04 LTS (focal) | 1:68.10.0+build1-0ubuntu0.20.04.1 | [xul-ext-lightning 1:68.10.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-lightning-1-68.10.0-build1-0ubuntu0.20.04.1.md) | Oct 8, 2020 | --- Data as of 2026-11-08T13:06:02Z UTC. 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