CVE-2025-1941: Mozilla Firefox Auth Bypass Vulnerability

CVE-2025-1941 Overview

CVE-2025-1941 is an authentication bypass vulnerability affecting Mozilla Firefox. Under certain circumstances, a user opt-in setting requiring authentication before using Focus could be bypassed. The flaw is distinct from CVE-2025-0245 and was fixed in Firefox 136. The weakness maps to CWE-284: Improper Access Control.

Mozilla addressed the issue in security advisory MFSA-2025-14. No public proof-of-concept or in-the-wild exploitation has been reported, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Critical Impact
Attackers can bypass a user-configured authentication requirement protecting the Focus feature in Firefox, undermining a privacy control intended to gate access to sensitive browsing data.

Affected Products

Mozilla Firefox versions prior to 136
CPE: cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
Component: mozilla:firefox

Discovery Timeline

2025-03-04 - CVE-2025-1941 published to NVD
2026-04-13 - Last updated in NVD database

Technical Details for CVE-2025-1941

Vulnerability Analysis

The vulnerability resides in the authentication enforcement logic governing the Focus feature in Firefox. Users can opt in to require authentication before Focus is accessible. Under specific conditions, this control fails to enforce the authentication step. An attacker reaching the device or interacting with the affected workflow can use Focus without satisfying the configured authentication requirement.

This issue is tracked in Mozilla Bug Report #1944665 and is classified separately from CVE-2025-0245, which addressed a related but distinct bypass path.

Root Cause

The root cause is improper access control [CWE-284]. The authentication gate covering the Focus opt-in setting is not consistently applied across all entry paths into the feature. The control depends on conditional logic that can be skipped, leaving the protected functionality reachable without the required credential check.

Attack Vector

The CVSS vector indicates a network-reachable attack path with no privileges or user interaction required. Successful exploitation undermines confidentiality and integrity by exposing functionality that the user explicitly chose to protect behind authentication. Availability is not impacted. No public exploit code is available for this issue.

No verified proof-of-concept code is published. The vulnerability mechanism is described in Mozilla's bug tracker and the corresponding security advisory.

Detection Methods for CVE-2025-1941

Indicators of Compromise

No public indicators of compromise have been published for CVE-2025-1941.
Mozilla has not reported observed exploitation in the wild.

Detection Strategies

Inventory all Firefox installations across the environment and compare installed versions against the fixed version 136 or later.
Use software asset management telemetry to flag endpoints running Firefox builds older than 136.
Review browser update logs for failed or deferred Firefox updates that could leave systems exposed.

Monitoring Recommendations

Monitor endpoint management systems for Firefox version drift and out-of-date installations.
Track Mozilla security advisory feeds and the MFSA-2025-14 bulletin for additional guidance.
Audit user-configured Firefox security settings during routine endpoint compliance checks.

How to Mitigate CVE-2025-1941

Immediate Actions Required

Update Mozilla Firefox to version 136 or later on all managed endpoints.
Confirm automatic updates are enabled so that future security releases install without delay.
Validate that the Focus authentication opt-in setting behaves as expected after patching.

Patch Information

Mozilla fixed CVE-2025-1941 in Firefox 136. Full remediation details are available in Mozilla Security Advisory MFSA-2025-14 and the underlying Mozilla Bug Report #1944665.

Workarounds

No vendor-supplied workaround exists. Upgrading to Firefox 136 or later is the only supported remediation.
Until patching is complete, avoid relying on the Focus authentication opt-in as a sole control for sensitive workflows.

bash

# Verify the installed Firefox version on Linux/macOS
firefox --version

# Windows: query the installed version from the registry
reg query "HKLM\SOFTWARE\Mozilla\Mozilla Firefox" /v CurrentVersion