CVE-2021-29987

MEDIUM

Firefox < 91.0 - Permission Panel Clickjacking via Overlapping UI

Title source: llm
STIX 2.1

Description

After requesting multiple permissions, and closing the first permission panel, subsequent permission panels will be displayed in a different position but still record a click in the default location, making it possible to trick a user into accepting a permission they did not want to. *This bug only affects Firefox on Linux. Other operating systems are unaffected.*. This vulnerability affects Firefox < 91 and Thunderbird < 91.

References (4)

Core 4
Core References
Issue Tracking, Vendor Advisory x_refsource_misc
https://bugzilla.mozilla.org/show_bug.cgi?id=1716129
Third Party Advisory vendor-advisory x_refsource_gentoo
https://security.gentoo.org/glsa/202202-03

Scores

CVSS v3 6.5
EPSS 0.0031
EPSS Percentile 54.3%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Details

CWE
CWE-307
Status published
Products (2)
mozilla/firefox < 91.0
mozilla/thunderbird < 91.0
Published Aug 17, 2021
Tracked Since Feb 18, 2026