Cyber Resilience

CVE-2026-74978

Mozilla Firefox ≤ 153.1.0

Published
18 August 2026
Modified
25 August 2026
Patch / advisory
View advisory
CVSS Score v3.1 8.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
EPSS Score 0.0023 14th percentile
Risk Priority 58 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-74978 is a high-severity Improper Restriction of Rendered UI Layers or Frames (CWE-1021) vulnerability in Mozilla Firefox. Its CVSS base score is 8.1 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Input Capture (T1056); ranked at the 14th 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

Clickjacking issue in the Widget component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

CWE(s)
CWE-1021

Related Threats

MITRE ATT&CK Enterprise Techniques

T1056 Input Capture Collection
Adversaries may use methods of capturing user input to obtain credentials or collect information.
attack.mitre.org →
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 →
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-2024-11695Same product: Mozilla Firefox
CVE-2026-12322Same product: Mozilla Firefox
CVE-2026-74958Same product: Mozilla Firefox
CVE-2024-11700Same product: Mozilla Firefox
CVE-2025-1019Same product: Mozilla Firefox
CVE-2026-12323Same product: Mozilla Firefox
CVE-2026-84139Same product: Mozilla Firefox
CVE-2025-1018Same product: Mozilla Firefox
CVE-2024-7518Same product: Mozilla Firefox
CVE-2023-25730Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 153.1.0
mozilla
thunderbird
≤ 153.1.0

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 partial 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.8.23 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.

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

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

References