# CVE-2021-29986: firefox: Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability. This... CVE-2021-29986 is fixed in 9 products on 1 platform, first by firefox 91.0+build2-0ubuntu0.18.04.1, released August 10, 2021. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2021-29986 - Priority: High - CVSS: 8.1 (Important) - EPSS: 0.0126 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Aug 10, 2021 ## Description Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability. This update upgrades Firefox to version 78.13.0 ESR. Security Fix(es): * Mozilla: Uninitialized memory in a canvas object could have led to memory corruption (CVE-2021-29980) * Mozilla: Incorrect instruction reordering during JIT optimization (CVE-2021-29984) * Mozilla: Race condition when resolving DNS names could have led to memory corruption (CVE-2021-29986) * Mozilla: Memory corruption as a result of incorrect style treatment (CVE-2021-29988) * Mozilla: Memory safety bugs fixed in Thunderbird 78.13 (CVE-2021-29989) * Mozilla: Use-after-free media channels (CVE-2021-29985) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | firefox RHEL 8 | 0:78.13.0-2.el8_4 | [RHSA-2021:3157](https://patchblox.com/security/data/fix/linux/rhsa-2021-3157.md) | Aug 16, 2021 | | Linux | firefox Ubuntu 18.04.6 LTS (bionic) | 91.0+build2-0ubuntu0.18.04.1 | [firefox 91.0+build2-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-91.0-build2-0ubuntu0.18.04.1.md) | Aug 10, 2021 | | Linux | firefox Ubuntu 20.04 LTS (focal) | 91.0+build2-0ubuntu0.20.04.1 | [firefox 91.0+build2-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-91.0-build2-0ubuntu0.20.04.1.md) | Aug 10, 2021 | | Linux | firefox ol 8 | 0:78.13.0-2.0.1.el8_4 | [ELSA-2021-3157](https://patchblox.com/security/data/fix/linux/elsa-2021-3157.md) | Aug 17, 2021 | | Linux | firefox-geckodriver Ubuntu 18.04.6 LTS (bionic) | 91.0+build2-0ubuntu0.18.04.1 | [firefox-geckodriver 91.0+build2-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-geckodriver-91.0-build2-0ubuntu0.18.04.1.md) | Aug 10, 2021 | | Linux | firefox-geckodriver Ubuntu 20.04 LTS (focal) | 91.0+build2-0ubuntu0.20.04.1 | [firefox-geckodriver 91.0+build2-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-geckodriver-91.0-build2-0ubuntu0.20.04.1.md) | Aug 10, 2021 | | Linux | firefox-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 91.0+build2-0ubuntu0.18.04.1 | [firefox-mozsymbols 91.0+build2-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-mozsymbols-91.0-build2-0ubuntu0.18.04.1.md) | Aug 10, 2021 | | Linux | firefox-mozsymbols Ubuntu 20.04 LTS (focal) | 91.0+build2-0ubuntu0.20.04.1 | [firefox-mozsymbols 91.0+build2-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-mozsymbols-91.0-build2-0ubuntu0.20.04.1.md) | Aug 10, 2021 | | Linux | thunderbird RHEL 8 | 0:78.13.0-1.el8_4 | [RHSA-2021:3155](https://patchblox.com/security/data/fix/linux/rhsa-2021-3155.md) | Aug 16, 2021 | | Linux | thunderbird Ubuntu 18.04.6 LTS (bionic) | 1:78.13.0+build1-0ubuntu0.18.04.1 | [thunderbird 1:78.13.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-1-78.13.0-build1-0ubuntu0.18.04.1.md) | Aug 10, 2021 | | Linux | thunderbird Ubuntu 20.04 LTS (focal) | 1:78.13.0+build1-0ubuntu0.20.04.2 | [thunderbird 1:78.13.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-1-78.13.0-build1-0ubuntu0.20.04.2.md) | Aug 10, 2021 | | Linux | thunderbird ol 8 | 0:78.13.0-1.0.1.el8_4 | [ELSA-2021-3155](https://patchblox.com/security/data/fix/linux/elsa-2021-3155.md) | Aug 17, 2021 | | Linux | thunderbird-gnome-support Ubuntu 18.04.6 LTS (bionic) | 1:78.13.0+build1-0ubuntu0.18.04.1 | [thunderbird-gnome-support 1:78.13.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-gnome-support-1-78.13.0-build1-0ubuntu0.18.04.1.md) | Aug 10, 2021 | | Linux | thunderbird-gnome-support Ubuntu 20.04 LTS (focal) | 1:78.13.0+build1-0ubuntu0.20.04.2 | [thunderbird-gnome-support 1:78.13.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-gnome-support-1-78.13.0-build1-0ubuntu0.20.04.2.md) | Aug 10, 2021 | | Linux | thunderbird-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 1:78.13.0+build1-0ubuntu0.18.04.1 | [thunderbird-mozsymbols 1:78.13.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-mozsymbols-1-78.13.0-build1-0ubuntu0.18.04.1.md) | Aug 10, 2021 | | Linux | thunderbird-mozsymbols Ubuntu 20.04 LTS (focal) | 1:78.13.0+build1-0ubuntu0.20.04.2 | [thunderbird-mozsymbols 1:78.13.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-mozsymbols-1-78.13.0-build1-0ubuntu0.20.04.2.md) | Aug 10, 2021 | | Linux | xul-ext-calendar-timezones Ubuntu 18.04.6 LTS (bionic) | 1:78.13.0+build1-0ubuntu0.18.04.1 | [xul-ext-calendar-timezones 1:78.13.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-calendar-timezones-1-78.13.0-build1-0ubuntu0.18.04.1.md) | Aug 10, 2021 | | Linux | xul-ext-calendar-timezones Ubuntu 20.04 LTS (focal) | 1:78.13.0+build1-0ubuntu0.20.04.2 | [xul-ext-calendar-timezones 1:78.13.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-calendar-timezones-1-78.13.0-build1-0ubuntu0.20.04.2.md) | Aug 10, 2021 | | Linux | xul-ext-gdata-provider Ubuntu 18.04.6 LTS (bionic) | 1:78.13.0+build1-0ubuntu0.18.04.1 | [xul-ext-gdata-provider 1:78.13.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-gdata-provider-1-78.13.0-build1-0ubuntu0.18.04.1.md) | Aug 10, 2021 | | Linux | xul-ext-gdata-provider Ubuntu 20.04 LTS (focal) | 1:78.13.0+build1-0ubuntu0.20.04.2 | [xul-ext-gdata-provider 1:78.13.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-gdata-provider-1-78.13.0-build1-0ubuntu0.20.04.2.md) | Aug 10, 2021 | | Linux | xul-ext-lightning Ubuntu 18.04.6 LTS (bionic) | 1:78.13.0+build1-0ubuntu0.18.04.1 | [xul-ext-lightning 1:78.13.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-lightning-1-78.13.0-build1-0ubuntu0.18.04.1.md) | Aug 10, 2021 | | Linux | xul-ext-lightning Ubuntu 20.04 LTS (focal) | 1:78.13.0+build1-0ubuntu0.20.04.2 | [xul-ext-lightning 1:78.13.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-lightning-1-78.13.0-build1-0ubuntu0.20.04.2.md) | Aug 10, 2021 | --- Data as of 2026-11-09T01:18:40Z UTC. 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