CVE-2021-38503
firefox-esr - security update
10.0
CRITICAL
CVSS 3.1
EPSS 1.2%
Description
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.
How to fix CVE-2021-38503
To remediate CVE-2021-38503, upgrade the affected package to a fixed version below.
- Debian/firefox-esr—upgrade to 91.4.1esr-1~deb11u1 or later
- —upgrade to 91.4.1esr-1~deb9u1 or later
- —upgrade to 91.4.1esr-1~deb11u1 or later
- —upgrade to 1:91.4.1-1~deb11u1 or later
Is CVE-2021-38503 being exploited?
Low — EPSS is 1.2%, meaning exploitation activity has not been observed at scale.
Affected packages (4)
- from 0, < 91.4.1esr-1~deb11u1
- from 0, < 91.4.1esr-1~deb9u1
- from 0, < 91.4.1esr-1~deb11u1
- from 0, < 1:91.4.1-1~deb11u1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | CRITICAL10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |