Edge of Danger: Unpacking CVE-2025-29834's Out-of-Bounds Read in Microsoft Edge
Introduction
Microsoft Edge users face a critical threat with CVE-2025-29834, an out-of-bounds read vulnerability that could allow attackers to execute arbitrary code remotely. This flaw, rated at a CVSS score of 7.5, underscores the persistent security challenges in Chromium-based browsers and demands immediate attention from security professionals.
Affected Systems and Versions
The vulnerability specifically impacts Microsoft Edge (Chromium-based) versions prior to 135.0.2789.91. All configurations running these versions are vulnerable and should be considered at risk.
Technical Information
CVE-2025-29834 stems from improper bounds checking within Edge's V8 JavaScript engine, particularly when parsing typed array buffers. Malicious JavaScript can exploit this flaw by creating oversized ArrayBuffer objects, allowing attackers to read memory beyond allocated boundaries. This unauthorized memory access can lead to sensitive data exposure and, when combined with heap-spraying techniques, arbitrary code execution.
Attack vectors include:
- Drive-by downloads via compromised websites
- Phishing attacks embedding malicious JavaScript
- Man-in-the-middle (MITM) attacks injecting payloads into unencrypted HTTP traffic
Successful exploitation grants attackers SYSTEM-level privileges on Windows 11 systems, significantly amplifying potential damage.
Patch Information
Microsoft has released a critical update addressing this vulnerability. Users must upgrade Microsoft Edge to version 135.0.2789.91 or later immediately. The update includes enhanced bounds-checking mechanisms within the V8 JavaScript engine.
Patch download and further details can be found here:
Alternative mitigations include:
- Enforcing HTTPS to prevent MITM attacks
- Deploying web application firewalls (WAFs)
- Enabling Enhanced Security Mode in Edge
- Disabling JavaScript execution for non-essential domains
- Activating Windows Defender Exploit Guard (WDEG)
Detection Methods
Currently, specific detection methods or indicators of compromise for CVE-2025-29834 have not been publicly detailed. Security teams should closely monitor Microsoft and trusted security advisories for updates on detection techniques and indicators of compromise.
Vendor Security History
Microsoft has previously addressed similar vulnerabilities, including CVE-2025-24201 and CVE-2025-1914, demonstrating a consistent response to Chromium-based security issues. However, the recurrence of memory corruption vulnerabilities highlights ongoing challenges in securing complex browser architectures.
References
Security professionals must act swiftly to apply the available patch and implement recommended mitigations to safeguard against potential exploitation of CVE-2025-29834.
