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.
https://www.mozilla.org/security/advisories/mfsa2021-50/
https://bugzilla.mozilla.org/show_bug.cgi?id=1729517
https://www.mozilla.org/security/advisories/mfsa2021-49/
https://www.mozilla.org/security/advisories/mfsa2021-48/
https://www.debian.org/security/2021/dsa-5026
https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html
https://www.debian.org/security/2022/dsa-5034
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html
Source: MITRE
Published: 2021-12-08
Updated: 2022-12-09
Type: CWE-863
Base Score: 7.5
Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 10
Severity: HIGH
Base Score: 10
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Impact Score: 6
Exploitability Score: 3.9
Severity: CRITICAL