CVE-2025-9479: Google Chrome V8 RCE Vulnerability

CVE-2025-9479 Overview

CVE-2025-9479 is an out-of-bounds read vulnerability [CWE-125] in the V8 JavaScript engine used by Google Chrome. The flaw affects versions of Chrome prior to 133.0.6943.141 across Windows, macOS, and Linux. A remote attacker can exploit the vulnerability by luring a user to a crafted HTML page. Successful exploitation can lead to heap corruption within the renderer process. Google categorized the Chromium security severity as Medium.

Critical Impact
A remote attacker can trigger heap corruption in the V8 engine through a malicious web page, potentially destabilizing the browser process and enabling further exploitation chains.

Affected Products

Google Chrome prior to 133.0.6943.141 on Microsoft Windows
Google Chrome prior to 133.0.6943.141 on Apple macOS
Google Chrome prior to 133.0.6943.141 on Linux

Discovery Timeline

2025-11-14 - CVE-2025-9479 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-9479

Vulnerability Analysis

CVE-2025-9479 resides in V8, the JavaScript and WebAssembly engine that powers Chrome and Chromium-based browsers. The engine performs an out-of-bounds read that reaches memory outside the bounds of an allocated buffer. Reads beyond intended boundaries can leak adjacent heap contents and destabilize object metadata used by the engine.

Because V8 processes untrusted script from any visited web page, the attack surface is broad. A crafted HTML page containing malicious JavaScript can steer V8 into the vulnerable code path during parsing, compilation, or execution. The read primitive can be used to disclose sensitive in-process data or corrupt heap structures that V8 relies on for type safety.

Root Cause

The vulnerability stems from missing or incorrect bounds validation in V8 when accessing memory. The engine reads memory past the intended object or buffer boundary, violating the classic weakness pattern described in [CWE-125]. In managed runtimes such as V8, out-of-bounds reads frequently intersect with hidden class assumptions and inline caches, which can then be manipulated to escalate the primitive into heap corruption.

Attack Vector

Exploitation requires user interaction. The victim must visit a page controlled by the attacker or load attacker-supplied content in an existing tab. No authentication or elevated privileges are required. The attack is limited to the renderer sandbox unless combined with a sandbox escape.

No verified public proof-of-concept code is available for CVE-2025-9479. Technical details are tracked in the Chromium Issue Tracker Entry.

Detection Methods for CVE-2025-9479

Indicators of Compromise

Unexpected Chrome renderer process crashes with signatures pointing to V8 memory access violations.
Browser telemetry showing repeated navigations to unfamiliar domains hosting heavy JavaScript payloads immediately before renderer instability.
Outbound connections from Chrome to newly registered or low-reputation domains delivering obfuscated JavaScript.

Detection Strategies

Inventory installed Chrome builds across the estate and flag any version below 133.0.6943.141 as vulnerable.
Monitor Windows Error Reporting, macOS ReportCrash, and Linux core dumps for Chrome renderer crashes referencing V8 modules.
Correlate web proxy logs with endpoint browser process events to identify sessions where a crash follows a specific URL visit.

Monitoring Recommendations

Enable Chrome enterprise reporting to centralize crash and version telemetry.
Alert on chrome.exe, Google Chrome, or chrome binary child processes exhibiting abnormal memory faults.
Track JavaScript-heavy domains categorized as uncategorized or newly seen and prioritize them for URL filtering review.

How to Mitigate CVE-2025-9479

Immediate Actions Required

Update Google Chrome to version 133.0.6943.141 or later on all Windows, macOS, and Linux endpoints.
Restart the browser after the update to ensure the patched V8 binary is loaded into memory.
Verify managed deployments through Chrome Browser Cloud Management or equivalent MDM policies.

Patch Information

Google released the fix in the Chrome Stable channel update for desktop. Administrators should reference the Google Chrome Update Announcement for release notes and rollout guidance. Chromium-based browsers that consume the upstream V8 fix should also be updated to a build that incorporates the patched engine.

Workarounds

Enforce automatic Chrome updates through group policy or MDM to prevent version drift.
Restrict browsing to trusted domains via URL filtering until patching is complete on all endpoints.
Disable JavaScript on high-risk or unmanaged sites through Chrome policy DefaultJavaScriptSetting where operationally feasible.

bash

# Verify installed Chrome version on Linux/macOS endpoints
google-chrome --version

# Windows registry check for managed Chrome version
reg query "HKLM\SOFTWARE\Google\Update\Clients\{8A69D345-D564-463C-AFF1-A69D9E530F96}" /v pv