CVE-2021-38503
Mozilla Firefox ESR and 3 others: The iframe sandbox rules were not correctly applied to XSLT stylesheets, allowing an iframe to bypass…
CVE-2021-38503 is fixed in 12 products on 2 platforms, first by Mozilla Thunderbird (en-US) 91.3.0, released November 1, 2021. It is not reported as exploited. Patch Radar priority: High.
HighFixed on 2 platforms
CVSS
10.0
Important
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0412
90th percentile
The iframe sandbox rules were not correctly applied to XSLT stylesheets, allowing an iframe to bypass restrictions such as executing scripts or navigating the top-level frame. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Windows apps | |||
| Mozilla Firefox ESR (en-US) | 102.0 | Mozilla Firefox ESR (en-US) 102.0 | Jun 23, 2022 |
| Mozilla Thunderbird (en-US) | 91.3.0 | Mozilla Thunderbird (en-US) 91.3.0 | Nov 1, 2021 |
| Linux | |||
| firefox · RHEL 8 | 0:91.3.0-1.el8_4 | RHSA-2021:4123 | Nov 3, 2021 |
| firefox · Ubuntu 18.04.6 LTS (bionic) | 94.0+build3-0ubuntu0.18.04.1 | firefox 94.0+build3-0ubuntu0.18.04.1 | Nov 2, 2021 |
| firefox · Ubuntu 20.04 LTS (focal) | 94.0+build3-0ubuntu0.20.04.1 | firefox 94.0+build3-0ubuntu0.20.04.1 | Nov 2, 2021 |
| firefox · Ubuntu 22.04.1 LTS (jammy) | 94.0+build3-0ubuntu1 | firefox 94.0+build3-0ubuntu1 | Nov 2, 2021 |
| firefox · ol 8 | 0:91.3.0-1.0.1.el8_4 | ELSA-2021-4123 | Nov 4, 2021 |
| firefox-esr · Debian 11.6 (bullseye) | 91.4.1esr-1~deb11u1 | DSA-5026-1 | Dec 19, 2021 |
| firefox-esr · Debian 12.15 (bookworm) | 91.3.0esr-1 | DEBIAN-CVE-2021-38503 | Dec 8, 2021 |
| firefox-esr · Debian 13.5 (trixie) | 91.3.0esr-1 | DEBIAN-CVE-2021-38503 | Dec 8, 2021 |
| firefox-esr · Debian 14 | 91.3.0esr-1 | DEBIAN-CVE-2021-38503 | Dec 8, 2021 |
| firefox-geckodriver · Ubuntu 18.04.6 LTS (bionic) | 94.0+build3-0ubuntu0.18.04.1 | firefox-geckodriver 94.0+build3-0ubuntu0.18.04.1 | Nov 2, 2021 |
| firefox-geckodriver · Ubuntu 20.04 LTS (focal) | 94.0+build3-0ubuntu0.20.04.1 | firefox-geckodriver 94.0+build3-0ubuntu0.20.04.1 | Nov 2, 2021 |
| firefox-geckodriver · Ubuntu 22.04.1 LTS (jammy) | 94.0+build3-0ubuntu1 | firefox-geckodriver 94.0+build3-0ubuntu1 | Nov 2, 2021 |
| firefox-mozsymbols · Ubuntu 18.04.6 LTS (bionic) | 94.0+build3-0ubuntu0.18.04.1 | firefox-mozsymbols 94.0+build3-0ubuntu0.18.04.1 | Nov 2, 2021 |
| firefox-mozsymbols · Ubuntu 20.04 LTS (focal) | 94.0+build3-0ubuntu0.20.04.1 | firefox-mozsymbols 94.0+build3-0ubuntu0.20.04.1 | Nov 2, 2021 |
| firefox-mozsymbols · Ubuntu 22.04.1 LTS (jammy) | 94.0+build3-0ubuntu1 | firefox-mozsymbols 94.0+build3-0ubuntu1 | Nov 2, 2021 |
| thunderbird · Debian 12.15 (bookworm) | 1:91.3.0-1 | DEBIAN-CVE-2021-38503 | Dec 8, 2021 |
| thunderbird · Debian 13.5 (trixie) | 1:91.3.0-1 | DEBIAN-CVE-2021-38503 | Dec 8, 2021 |
| thunderbird · Debian 14 | 1:91.3.0-1 | DEBIAN-CVE-2021-38503 | Dec 8, 2021 |
| thunderbird · RHEL 8 | 0:91.3.0-2.el8_4 | RHSA-2021:4130 | Nov 4, 2021 |
| thunderbird · Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | thunderbird 1:91.5.0+build1-0ubuntu0.18.04.1 | Feb 16, 2023 |
| thunderbird · Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | thunderbird 1:91.5.0+build1-0ubuntu0.20.04.1 | Feb 16, 2023 |
| thunderbird · Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | thunderbird 1:91.3.1+build1-0ubuntu1 | Nov 2, 2021 |
| thunderbird · ol 8 | 0:91.3.0-2.0.1.el8_4 | ELSA-2021-4130 | Nov 5, 2021 |
| thunderbird-gnome-support · Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | thunderbird-gnome-support 1:91.5.0+build1-0ubuntu0.18.04.1 | Feb 16, 2023 |
| thunderbird-gnome-support · Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | thunderbird-gnome-support 1:91.5.0+build1-0ubuntu0.20.04.1 | Feb 16, 2023 |
| thunderbird-gnome-support · Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | thunderbird-gnome-support 1:91.3.1+build1-0ubuntu1 | Nov 2, 2021 |
| thunderbird-mozsymbols · Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | thunderbird-mozsymbols 1:91.5.0+build1-0ubuntu0.18.04.1 | Feb 16, 2023 |
| thunderbird-mozsymbols · Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | thunderbird-mozsymbols 1:91.5.0+build1-0ubuntu0.20.04.1 | Feb 16, 2023 |
| thunderbird-mozsymbols · Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | thunderbird-mozsymbols 1:91.3.1+build1-0ubuntu1 | Nov 2, 2021 |
| xul-ext-calendar-timezones · Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | xul-ext-calendar-timezones 1:91.5.0+build1-0ubuntu0.18.04.1 | Feb 16, 2023 |
| xul-ext-calendar-timezones · Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | xul-ext-calendar-timezones 1:91.5.0+build1-0ubuntu0.20.04.1 | Feb 16, 2023 |
| xul-ext-calendar-timezones · Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | xul-ext-calendar-timezones 1:91.3.1+build1-0ubuntu1 | Nov 2, 2021 |
| xul-ext-gdata-provider · Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | xul-ext-gdata-provider 1:91.5.0+build1-0ubuntu0.18.04.1 | Feb 16, 2023 |
| xul-ext-gdata-provider · Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | xul-ext-gdata-provider 1:91.5.0+build1-0ubuntu0.20.04.1 | Feb 16, 2023 |
| xul-ext-gdata-provider · Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | xul-ext-gdata-provider 1:91.3.1+build1-0ubuntu1 | Nov 2, 2021 |
| xul-ext-lightning · Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | xul-ext-lightning 1:91.5.0+build1-0ubuntu0.18.04.1 | Feb 16, 2023 |
| xul-ext-lightning · Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | xul-ext-lightning 1:91.5.0+build1-0ubuntu0.20.04.1 | Feb 16, 2023 |
| xul-ext-lightning · Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | xul-ext-lightning 1:91.3.1+build1-0ubuntu1 | Nov 2, 2021 |
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