CVE-2025-3608 in Firefox
Summary
by MITRE • 04/15/2025
A race condition existed in nsHttpTransaction that could have been exploited to cause memory corruption, potentially leading to an exploitable condition. This vulnerability was fixed in Firefox 137.0.2.
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Analysis
by VulDB Data Team • 04/15/2026
The vulnerability identified as CVE-2025-3608 represents a critical race condition within the nsHttpTransaction component of Mozilla Firefox, a fundamental web browser engine that handles HTTP protocol operations. This flaw emerged in the browser's networking stack where concurrent operations could lead to unpredictable memory access patterns, creating an environment ripe for exploitation. The race condition specifically manifested in the timing-dependent execution of HTTP transaction processing, where multiple threads or processes could simultaneously access shared memory resources without proper synchronization mechanisms. Such conditions are particularly dangerous in web browsers where complex interactions between various subsystems occur continuously during page loading and resource fetching operations. The vulnerability existed in Firefox versions prior to 137.0.2, indicating a window of exposure where users were potentially at risk from attackers who could craft malicious web content to trigger the exploitable state.
The technical implementation of this race condition stems from inadequate thread synchronization within the nsHttpTransaction class which manages HTTP request and response handling. When multiple threads attempt to modify shared data structures simultaneously, the lack of proper locking mechanisms can result in data corruption, memory inconsistency, and potentially arbitrary code execution. The flaw falls under the CWE-362 category of "Concurrent Execution using Shared Resource with Improper Synchronization" which specifically addresses the dangers of race conditions in multi-threaded environments. This vulnerability demonstrates how seemingly routine HTTP operations can become attack vectors when proper concurrency controls are absent, particularly when dealing with memory management and resource allocation in the browser's core networking components. The nature of the flaw suggests that attackers could manipulate the timing of HTTP requests and responses to force the browser into an inconsistent state where memory corruption occurs.
The operational impact of CVE-2025-3608 extends beyond simple browser instability, presenting a significant threat to user security and system integrity. When exploited successfully, this race condition could enable attackers to execute arbitrary code within the context of the browser process, potentially leading to complete system compromise. The vulnerability's exploitation would likely follow attack patterns consistent with the ATT&CK framework's T1059.007 technique for command and scripting interpreter, where attackers could leverage the corrupted memory state to inject malicious code. Users operating affected Firefox versions faced exposure to various attack vectors including drive-by downloads, malicious websites, and social engineering campaigns designed to trigger the race condition. The impact is particularly severe given that browsers serve as primary attack surfaces for cybercriminals, with this vulnerability potentially allowing for privilege escalation, data exfiltration, and persistent access to compromised systems. Security researchers identified this issue through careful analysis of memory access patterns and concurrent thread behavior during HTTP transaction processing.
Mitigation strategies for CVE-2025-3608 center on immediate patch deployment and system hardening measures. The most effective solution involves upgrading to Firefox version 137.0.2 or later, which incorporates proper synchronization mechanisms and memory management controls within the nsHttpTransaction component. Organizations should implement automated update policies to ensure all browser installations remain current with security patches. Additional protective measures include enabling browser security features such as sandboxing, content security policies, and strict MIME type checking to reduce the attack surface. Network-level protections such as web application firewalls and intrusion detection systems can help identify and block exploitation attempts targeting this vulnerability. Security teams should also conduct regular vulnerability assessments focusing on concurrent execution patterns in browser components, implementing monitoring for unusual memory access patterns that might indicate race condition exploitation attempts. The fix addresses the root cause by introducing proper mutex locking and atomic operations within the HTTP transaction processing pipeline, ensuring that shared resources are accessed in a controlled and predictable manner. This remediation aligns with industry best practices for preventing race conditions in multi-threaded applications and demonstrates the importance of thorough concurrency testing in complex software systems.