Firefox Addresses Severe Race Condition Vulnerability to Prevent Memory Corruption

On April 15, 2025, Mozilla released Firefox 137.0.2, addressing a critical security vulnerability tracked as CVE-2025-3608.

This flaw, classified with a “high” impact rating, was discovered in the nsHttpTransaction component—the core module responsible for handling HTTP transactions within the browser.

Technical Details: Race Condition and Memory Corruption

A race condition occurs when multiple threads or processes attempt to access shared resources simultaneously, resulting in unpredictable behavior.

In this case, the vulnerability was found in nsHttpTransaction, a critical part of Firefox’s network stack.

If exploited, this race condition could lead to memory corruption—a state where the contents of memory are unintentionally modified, potentially allowing attackers to execute arbitrary code or crash the browser.

The Mozilla Fuzzing Team, credited with reporting the issue, identified that the flaw could be triggered under specific timing conditions, making it difficult to exploit but dangerous due to its potential for remote code execution.

The vulnerability affects all Firefox versions before 137.0.2, making timely updates essential.

Security Impact and Risk Assessment

Mozilla assigned a “high” severity to CVE-2025-3608, reflecting the risk of memory corruption and the possibility of further exploitation.

According to CVSS v3.0 metrics, the vulnerability carries a base score of 8.1, indicating a significant threat level.

The attack vector is remote (AV:N), with high impact on confidentiality, integrity, and availability (C:H/I:H/A:H), but exploitation requires a high degree of attacker skill (AC:H).

The vulnerability does not require authentication (PR:N) or user interaction (UI:N), further elevating its risk profile.

Fortunately, as of the update, no known exploits have been reported in the wild, but users are strongly advised to update immediately.

Additional Fixes in Firefox 137.0.2

Beyond the critical security patch, Firefox 137.0.2 includes several bug fixes and improvements:

• Resolved frequent restarts during update processes.
• Fixed DRM playback issues related to Microsoft PlayReady.
• Addressed problems with HTML5 video player interactions.
• Improved accessibility in the PDF signature feature.
• Corrected issues with file picker display and context menu paste operations.

Mozilla’s Response and User Recommendations

Mozilla acted swiftly, releasing the patch within days of the vulnerability’s discovery.

The update is available across all supported platforms, and users can download it via the official website or through automatic browser updates.

Risk Factor Table: CVE-2025-3608

Risk Factor	Value/Description
CVE Identifier	CVE-2025-3608
Component	nsHttpTransaction
Severity	High
CVSS v3.0 Score	8.1
Attack Vector	Network (AV:N)
Attack Complexity	High (AC:H)
Privileges Req.	None (PR:N)
User Interaction	None (UI:N)
Confidentiality	High (C:H)
Integrity	High (I:H)
Availability	High (A:H)
Exploits Known	None as of April 16, 2025
Fixed in Version	Firefox 137.0.2
Patch Date	April 15, 2025

The rapid release of Firefox 137.0.2 underscores Mozilla’s commitment to browser security.

Users and system administrators are urged to update immediately to mitigate the risk associated with CVE-2025-3608.

Staying current with browser updates remains the most effective defense against emerging threats.

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