CVE-2026-16396

Modified Modified - Updated After Analysis

Privilege Escalation in Firefox WebExtensions

Publication date: 2026-07-21

Last updated on: 2026-07-24

Assigner: Mozilla Corporation

Description

Privilege escalation in WebExtensions. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-07-21

Last Modified

2026-07-24

Generated

2026-08-10

AI Q&A

2026-07-21

EPSS Evaluated

2026-08-09

NVD

CVE-2026-16396

EUVD

EUVD-2026-46234

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	to 153.0.0 (exc)
mozilla	firefox	to 140.13.0 (exc)
mozilla	thunderbird	to 140.13.0 (exc)
mozilla	thunderbird	From 141.0 (inc) to 153.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-269	The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

Attack-Flow Graph

Executive Summary

This is a privilege escalation vulnerability in WebExtensions, which are browser extensions for Firefox. It allows an attacker with limited permissions to gain higher privileges within the browser, potentially executing unauthorized actions.

Detection Guidance

This vulnerability is fixed in Firefox 153 and Firefox ESR 140.13. To detect it, check your installed Firefox version using commands like 'firefox --version' or 'about:support' in Firefox. If your version is below these numbers, the system is vulnerable.

Impact Analysis

If exploited, this vulnerability could allow an attacker to perform actions on your behalf within the browser, such as accessing sensitive data, modifying browser settings, or installing malicious extensions without your consent.

Compliance Impact

The provided CVE data does not specify how this vulnerability impacts compliance with standards like GDPR or HIPAA. The description only mentions privilege escalation in WebExtensions without details on data exposure or regulatory implications.

Mitigation Strategies

Update Firefox to version 153 or later and Firefox ESR to version 140.13 or later to address the privilege escalation vulnerability in WebExtensions.

Hi! I’m here to help you understand CVE-2026-16396. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70