CVE-2021-38503

Critical

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.

SeverityCritical

CVSS10.0

Exploit probability—

Product

Mozilla Firefox

PublishedDec 8, 2021

First seenDec 8, 2021

How to fix

Update

mozilla firefox94.0 or later
mozilla firefox_esr91.3 or later
mozilla thunderbird91.3 or later

Vendor advisories

debian.org/security/2021/dsa-5026
debian.org/security/2022/dsa-5034
security.gentoo.org/glsa/202202-03
security.gentoo.org/glsa/202208-14

Affected products

Product	Affected versions	Fixed in
mozilla firefox	v < 94.0	94.0
mozilla firefox_esr	v < 91.3	91.3
mozilla thunderbird	v < 91.3	91.3
debian debian_linux	9.0, 10.0, 11.0	—

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