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Affected Environment
Firefox before 150.0.1 and Firefox ESR before 140.10.1 and 115.35.1 are affected. Any endpoint using these versions may be exposed.
Threat Overview
Vulnerabilities may enable arbitrary code execution and sandbox escape via browser use. Attackers could gain user-level control of impacted systems.
Exposure Timeline
Issues and fixes were published by Mozilla and noted on 30 April 2026. Exposure continues until vulnerable Firefox and ESR builds are updated.
Attack Surface
Exposure arises when users browse the web with vulnerable Firefox or ESR. Drive-by compromise is possible via malicious or compromised sites.
Technical Root Cause
Flaws include incorrect boundary conditions in Audio/Video and WebRTC networking, plus multiple memory safety bugs in affected releases.
Exploitation Pathway
An attacker can exploit these bugs during web browsing to run arbitrary code. With user privileges, they may install software or alter data.
Operational Impact
If exploited, attackers could view, change, or delete data and install programs. They could also create new accounts with the user’s level of rights.
Strategic Impact
Unpatched browsers increase risk of endpoint compromise via normal browsing. This weakens overall enterprise control of data and user accounts.
Required Mitigation
Update Firefox and Firefox ESR to the latest supported versions after testing. Enforce least privilege and ensure only supported browsers are used.
Incident Response Guidance
Check fleet for vulnerable Firefox/ESR builds and update them. Strengthen exploit protection, web filtering, endpoint controls, and user awareness.
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