Firefox ESR and 2 others: Firefox did not block execution of scripts with incorrect MIME types when the response was intercepted…
CVE-2020-26958 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.
Firefox did not block execution of scripts with incorrect MIME types when the response was intercepted and cached through a ServiceWorker. This could lead to a cross-site script inclusion vulnerability, or a Content Security Policy bypass. 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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