Vulnerabilities
Misconfiguration
Compliance
CVE Vulnerabilities

CVE-2021-38509

Improper Restriction of Rendered UI Layers or Frames

Published: Dec 08, 2021 | Modified: Nov 21, 2024
CVSS 3.x
4.3
MEDIUM
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
CVSS 2.x
4.3 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N
RedHat/V2
RedHat/V3
6.1 MODERATE
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Ubuntu
MEDIUM
Vulnerability-free packages from our partners
root.io logo minimus.io logo echo.ai logo
Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2021-38509
CWEhttps://cwe.mitre.org/data/definitions/1021.html

Due to an unusual sequence of attacker-controlled events, a Javascript alert() dialog with arbitrary (although unstyled) contents could be displayed over top an uncontrolled webpage of the attackers choosing. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

Weakness

The web application does not restrict or incorrectly restricts frame objects or UI layers that belong to another application or domain.

Affected Software

NameVendorStart VersionEnd Version
FirefoxMozilla*94.0 (excluding)
Firefox_esrMozilla*91.3.0 (excluding)
ThunderbirdMozilla*91.3.0 (excluding)
Red Hat Enterprise Linux 7RedHatfirefox-0:91.3.0-1.el7_9*
Red Hat Enterprise Linux 7RedHatthunderbird-0:91.3.0-2.el7_9*
Red Hat Enterprise Linux 8RedHatfirefox-0:91.3.0-1.el8_4*
Red Hat Enterprise Linux 8RedHatthunderbird-0:91.3.0-2.el8_4*
Red Hat Enterprise Linux 8.1 Extended Update SupportRedHatthunderbird-0:91.3.0-2.el8_1*
Red Hat Enterprise Linux 8.1 Extended Update SupportRedHatfirefox-0:91.3.0-1.el8_1*
Red Hat Enterprise Linux 8.2 Extended Update SupportRedHatthunderbird-0:91.3.0-2.el8_2*
Red Hat Enterprise Linux 8.2 Extended Update SupportRedHatfirefox-0:91.3.0-1.el8_2*
FirefoxUbuntubionic*
FirefoxUbuntudevel*
FirefoxUbuntufocal*
FirefoxUbuntuhirsute*
FirefoxUbuntuimpish*
FirefoxUbuntujammy*
FirefoxUbuntukinetic*
FirefoxUbuntulunar*
FirefoxUbuntumantic*
FirefoxUbuntunoble*
FirefoxUbuntutrusty*
FirefoxUbuntuupstream*
FirefoxUbuntuxenial*
Mozjs38Ubuntubionic*
Mozjs38Ubuntuesm-apps/bionic*
Mozjs38Ubuntuupstream*
Mozjs52Ubuntubionic*
Mozjs52Ubuntuesm-apps/focal*
Mozjs52Ubuntuesm-infra/bionic*
Mozjs52Ubuntufocal*
Mozjs52Ubuntuupstream*
Mozjs68Ubuntuesm-infra/focal*
Mozjs68Ubuntufocal*
Mozjs68Ubuntuupstream*
Mozjs78Ubuntuesm-apps/jammy*
Mozjs78Ubuntuhirsute*
Mozjs78Ubuntuimpish*
Mozjs78Ubuntujammy*
Mozjs78Ubuntukinetic*
Mozjs78Ubuntulunar*
Mozjs78Ubuntuupstream*
ThunderbirdUbuntubionic*
ThunderbirdUbuntudevel*
ThunderbirdUbuntufocal*
ThunderbirdUbuntuhirsute*
ThunderbirdUbuntuimpish*
ThunderbirdUbuntujammy*
ThunderbirdUbuntukinetic*
ThunderbirdUbuntulunar*
ThunderbirdUbuntumantic*
ThunderbirdUbuntunoble*
ThunderbirdUbuntutrusty*
ThunderbirdUbuntuupstream*
ThunderbirdUbuntuxenial*

Potential Mitigations

  • The use of X-Frame-Options allows developers of web content to restrict the usage of their application within the form of overlays, frames, or iFrames. The developer can indicate from which domains can frame the content.
  • The concept of X-Frame-Options is well documented, but implementation of this protection mechanism is in development to cover gaps. There is a need for allowing frames from multiple domains.
  • A developer can use a “frame-breaker” script in each page that should not be framed. This is very helpful for legacy browsers that do not support X-Frame-Options security feature previously mentioned.
  • It is also important to note that this tactic has been circumvented or bypassed. Improper usage of frames can persist in the web application through nested frames. The “frame-breaking” script does not intuitively account for multiple nested frames that can be presented to the user.

References

Aqua Security is the largest pure-play cloud native security company, providing customers the freedom to innovate and run their businesses with minimal friction. The Aqua Cloud Native Security Platform provides prevention, detection, and response automation across the entire application lifecycle to secure the build, secure cloud infrastructure and secure running workloads wherever they are deployed.
Copyright © 2026 Aqua Security Software Ltd.   Privacy Policy | Terms of Use