Introduction
Remote code execution through a single browser visit remains one of the most impactful attack vectors in modern enterprise security. A recent vulnerability in Google Chrome's V8 JavaScript engine, tracked as CVE-2025-9864, highlights the ongoing risks posed by memory safety issues in widely deployed software. Chrome is the dominant web browser globally, used by billions of individuals and organizations. Its V8 engine is also embedded in other Chromium-based browsers, amplifying the reach of any critical flaw.
Technical Information
CVE-2025-9864 is a use-after-free vulnerability in the V8 JavaScript engine, which is responsible for executing JavaScript code in Google Chrome. The vulnerability exists in Chrome versions prior to 140.0.7339.80. It is classified as CWE-416 (use-after-free) and carries a CVSS score of 8.8, reflecting its high severity.
The flaw occurs when memory allocated for certain objects in V8 is freed, but references to that memory persist elsewhere in the engine. If an attacker can trigger this condition, they can manipulate the memory region after it has been freed. By delivering a specially crafted HTML page containing malicious JavaScript, a remote attacker can exploit this use-after-free scenario to corrupt the heap. Successful exploitation may lead to arbitrary code execution within the context of the Chrome renderer process.
No public code snippets or detailed proof-of-concept exploit information are available for this vulnerability. The technical details remain limited to prevent weaponization, but the attack surface is well understood: remote attackers can target users simply by enticing them to visit a malicious or compromised website.
Patch Information
In the latest Chrome Stable Channel Update, version 139.0.7258.127/.128 for Windows and Mac, and 139.0.7258.127 for Linux, several critical security vulnerabilities have been addressed. (chromereleases.googleblog.com)
Heap Buffer Overflow in libaom (CVE-2025-8879): A heap buffer overflow vulnerability in libaom, the AV1 video codec library, was identified and patched. This flaw could have allowed attackers to execute arbitrary code by exploiting the overflow during video processing. The patch involved implementing additional boundary checks to prevent buffer overflows.
Race Condition in V8 (CVE-2025-8880): A race condition within the V8 JavaScript engine was discovered, which could lead to unexpected behavior or crashes. The fix addressed the synchronization issues by introducing proper locking mechanisms to ensure thread-safe operations.
Out of Bounds Write in ANGLE (CVE-2025-8901): An out-of-bounds write vulnerability in ANGLE, Chrome's graphics engine abstraction layer, was patched. This issue could have been exploited to corrupt memory, leading to potential code execution. The correction involved validating input data to prevent writing outside the allocated memory bounds.
Use After Free in Aura (CVE-2025-8882): A use-after-free vulnerability in Aura, Chrome's UI framework, was identified and fixed. This flaw could have been exploited to execute arbitrary code by accessing freed memory. The patch ensured that references to freed memory are properly handled to prevent such exploits.
These updates underscore the importance of timely software updates to maintain security and stability. Users are strongly encouraged to update their Chrome browsers to the latest version to benefit from these critical security fixes.
Reference: https://chromereleases.googleblog.com/2025/09/stable-channel-update-for-desktop.html
Detection Methods
Detecting exploitation of CVE-2025-9864, a use-after-free vulnerability in Google Chrome's V8 engine, requires a multifaceted approach combining network monitoring, system behavior analysis, and log examination. While specific detection signatures or indicators of compromise (IoCs) are not provided in the available sources, general strategies can be employed to identify potential exploitation attempts.
Network Monitoring:
Monitor for unusual outbound connections from Chrome processes, especially to unfamiliar or suspicious domains. Attackers often exploit browser vulnerabilities to initiate unauthorized network communications. Implementing network anomaly detection systems can help identify such irregular patterns.
System Behavior Analysis:
Utilize Endpoint Detection and Response (EDR) solutions to observe for abnormal behaviors in Chrome processes. Indicators may include unexpected process injections, unusual memory allocations, or the spawning of child processes that are atypical for standard browser operations. Behavioral analysis tools can flag these anomalies for further investigation.
Log Examination:
Regularly review system and application logs for signs of exploitation. Look for error messages or crash reports related to Chrome's V8 engine, as these could indicate attempts to exploit the use-after-free vulnerability. Additionally, monitor for any unauthorized changes to browser settings or extensions, which might suggest compromise.
Proactive Measures:
Ensure that all systems are updated to the latest version of Google Chrome, as patches addressing CVE-2025-9864 have been released. Educate users about the risks of visiting untrusted websites or downloading unknown files, as these actions can increase the likelihood of exploitation.
By integrating these detection methods into your security protocols, you can enhance your organization's ability to identify and respond to potential exploitation of CVE-2025-9864.
Affected Systems and Versions
- Google Chrome versions prior to 140.0.7339.80 are affected
- Chrome 140.0.7339.80 for Linux contains the fix
- Chrome 140.0.7339.80 and 140.0.7339.81 for Windows and Mac contain the fix
- All configurations running affected versions are vulnerable, including enterprise and consumer deployments
- Other Chromium-based browsers may also be affected if they have not incorporated the upstream patch
Vendor Security History
Google Chrome's V8 engine has been the subject of multiple high-severity vulnerabilities in recent years, including use-after-free and memory corruption bugs. Google typically releases patches within weeks of disclosure and maintains a public vulnerability reward program to encourage responsible reporting. Chrome's security architecture includes sandboxing and site isolation, but memory safety issues in V8 remain a recurring challenge.