Firefox ESR and 2 others: A parsing and event loading mismatch in Firefox's SVG code could have allowed load events to fire, even…
CVE-2020-26951 is fixed in 11 products on 2 platforms, first by firefox 83.0+build2-0ubuntu0.18.04.2, released November 16, 2020. It is not reported as exploited. Patch Radar priority: Routine.
A parsing and event loading mismatch in Firefox's SVG code could have allowed load events to fire, even after sanitization. An attacker already capable of exploiting an XSS vulnerability in privileged internal pages could have used this attack to bypass our built-in sanitizer. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Windows apps | |||
| Mozilla Firefox ESR (en-US) | 91.0 | Mozilla Firefox ESR (en-US) 91.0 | Aug 4, 2021 |
| Mozilla Thunderbird (en-US) | 78.10.0 | Mozilla Thunderbird (en-US) 78.10.0 | Apr 15, 2021 |
| Linux | |||
| firefox · RHEL 8 | 0:78.5.0-1.el8_3 | RHSA-2020:5237 | Nov 30, 2020 |
| firefox · Ubuntu 18.04.6 LTS (bionic) | 83.0+build2-0ubuntu0.18.04.2 | firefox 83.0+build2-0ubuntu0.18.04.2 | Nov 16, 2020 |
| firefox · Ubuntu 20.04 LTS (focal) | 83.0+build2-0ubuntu0.20.04.1 | firefox 83.0+build2-0ubuntu0.20.04.1 | Nov 16, 2020 |
| firefox · ol 8 | 0:78.5.0-1.0.1.el8_3 | ELSA-2020-5237 | Dec 1, 2020 |
| firefox-geckodriver · Ubuntu 18.04.6 LTS (bionic) | 83.0+build2-0ubuntu0.18.04.2 | firefox-geckodriver 83.0+build2-0ubuntu0.18.04.2 | Nov 16, 2020 |
| firefox-geckodriver · Ubuntu 20.04 LTS (focal) | 83.0+build2-0ubuntu0.20.04.1 | firefox-geckodriver 83.0+build2-0ubuntu0.20.04.1 | Nov 16, 2020 |
| firefox-mozsymbols · Ubuntu 18.04.6 LTS (bionic) | 83.0+build2-0ubuntu0.18.04.2 | firefox-mozsymbols 83.0+build2-0ubuntu0.18.04.2 | Nov 16, 2020 |
| firefox-mozsymbols · Ubuntu 20.04 LTS (focal) | 83.0+build2-0ubuntu0.20.04.1 | firefox-mozsymbols 83.0+build2-0ubuntu0.20.04.1 | Nov 16, 2020 |
| thunderbird · RHEL 8 | 0:78.5.0-1.el8_3 | RHSA-2020:5236 | Nov 30, 2020 |
| thunderbird · Ubuntu 18.04.6 LTS (bionic) | 1:78.8.1+build1-0ubuntu0.18.04.1 | thunderbird 1:78.8.1+build1-0ubuntu0.18.04.1 | Apr 22, 2021 |
| thunderbird · Ubuntu 20.04 LTS (focal) | 1:78.7.1+build1-0ubuntu0.20.04.1 | thunderbird 1:78.7.1+build1-0ubuntu0.20.04.1 | Jan 25, 2021 |
| thunderbird · ol 8 | 0:78.5.0-1.0.1.el8_3 | ELSA-2020-5236 | Dec 1, 2020 |
| thunderbird-gnome-support · Ubuntu 18.04.6 LTS (bionic) | 1:78.8.1+build1-0ubuntu0.18.04.1 | thunderbird-gnome-support 1:78.8.1+build1-0ubuntu0.18.04.1 | Apr 22, 2021 |
| thunderbird-gnome-support · Ubuntu 20.04 LTS (focal) | 1:78.7.1+build1-0ubuntu0.20.04.1 | thunderbird-gnome-support 1:78.7.1+build1-0ubuntu0.20.04.1 | Jan 25, 2021 |
| thunderbird-mozsymbols · Ubuntu 18.04.6 LTS (bionic) | 1:78.8.1+build1-0ubuntu0.18.04.1 | thunderbird-mozsymbols 1:78.8.1+build1-0ubuntu0.18.04.1 | Apr 22, 2021 |
| thunderbird-mozsymbols · Ubuntu 20.04 LTS (focal) | 1:78.7.1+build1-0ubuntu0.20.04.1 | thunderbird-mozsymbols 1:78.7.1+build1-0ubuntu0.20.04.1 | Jan 25, 2021 |
| xul-ext-calendar-timezones · Ubuntu 18.04.6 LTS (bionic) | 1:78.8.1+build1-0ubuntu0.18.04.1 | xul-ext-calendar-timezones 1:78.8.1+build1-0ubuntu0.18.04.1 | Apr 22, 2021 |
| xul-ext-calendar-timezones · Ubuntu 20.04 LTS (focal) | 1:78.7.1+build1-0ubuntu0.20.04.1 | xul-ext-calendar-timezones 1:78.7.1+build1-0ubuntu0.20.04.1 | Jan 25, 2021 |
| xul-ext-gdata-provider · Ubuntu 18.04.6 LTS (bionic) | 1:78.8.1+build1-0ubuntu0.18.04.1 | xul-ext-gdata-provider 1:78.8.1+build1-0ubuntu0.18.04.1 | Apr 22, 2021 |
| xul-ext-gdata-provider · Ubuntu 20.04 LTS (focal) | 1:78.7.1+build1-0ubuntu0.20.04.1 | xul-ext-gdata-provider 1:78.7.1+build1-0ubuntu0.20.04.1 | Jan 25, 2021 |
| xul-ext-lightning · Ubuntu 18.04.6 LTS (bionic) | 1:78.8.1+build1-0ubuntu0.18.04.1 | xul-ext-lightning 1:78.8.1+build1-0ubuntu0.18.04.1 | Apr 22, 2021 |
| xul-ext-lightning · Ubuntu 20.04 LTS (focal) | 1:78.7.1+build1-0ubuntu0.20.04.1 | xul-ext-lightning 1:78.7.1+build1-0ubuntu0.20.04.1 | Jan 25, 2021 |
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