CVE-2021-38506
Mozilla: Firefox could be coaxed into going into fullscreen mode without notification or warning
Severity
ImportantRed Hat Product Security
CVSS 3.0
Review impact separately from score.
Published · November 2, 2021
Updated · November 21, 2025
Description
The Mozilla Foundation Security Advisory describes this flaw as:
Through a series of navigations, Firefox could have entered fullscreen mode without notification or warning to the user. This could lead to spoofing attacks on the browser UI including phishing.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
No mitigation is specified in collected source.
CVSS / CWE
CVSS 3.0 · 7.5CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE-1021 · Improper Restriction of Rendered UI Layers or Frames