Cyber Resilience

CVE-2023-6211

Mozilla Firefox ≤ 120.0

Published
21 November 2023
Modified
21 November 2024
Patch / advisory
View advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
EPSS Score 0.0049 40th percentile
Risk Priority 50 floored blend · peak EPSS

Summary

CVE-2023-6211 is a medium-severity Improper Restriction of Rendered UI Layers or Frames (CWE-1021) vulnerability in Mozilla Firefox. Its CVSS base score is 6.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 40th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A06:2025 Insecure Design

EU & UK References

Vulnerability Data

If an attacker needed a user to load an insecure http: page and knew that user had enabled HTTPS-only mode, the attacker could have tricked the user into clicking to grant an HTTPS-only exception if they could get the user…

more

to participate in a clicking game. This vulnerability affects Firefox < 120.

CWE(s)
CWE-1021

Related Threats

MITRE ATT&CK Enterprise Techniques

T1189 Drive-by Compromise Initial Access
Adversaries may gain access to a system through a user visiting a website over the normal course of browsing.
attack.mitre.org →
T1056 Input Capture Collection
Adversaries may use methods of capturing user input to obtain credentials or collect information.
attack.mitre.org →
T1557 Adversary-in-the-Middle Credential Access
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-2613Same product: Mozilla Firefox
CVE-2025-6434Same product: Mozilla Firefox
CVE-2024-7523Same product: Mozilla Firefox
CVE-2025-1940Same product: Mozilla Firefox
CVE-2026-16397Same product: Mozilla Firefox
CVE-2024-10004Same product: Mozilla Firefox
CVE-2025-5267Same product: Mozilla Firefox
CVE-2023-25748Same product: Mozilla Firefox
CVE-2024-53976Same product: Mozilla Firefox
CVE-2023-37455Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 120.0

Mitigating Controls

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require implementing frame-ancestors / X-Frame-Options controls that prevent this weakness.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect missing frame protections, but does not itself implement the control.

A.8.23 Web filtering partial match
degrades

Web filtering can block or sandbox untrusted frames, but does not enforce application-level frame-busting or CSP.

A.8.26 Application security requirements partial match
prevents

Application security requirements can mandate frame-ancestors / X-Frame-Options, directly addressing UI redressing risks.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles include isolation of UI layers and proper use of browser security controls.

A.8.28 Secure coding partial match
prevents

Secure coding practices directly require implementation of frame-busting headers or CSP frame-ancestors directives.

References