CVE-2025-3070 Overview
CVE-2025-3070 is an input validation vulnerability in the Extensions component of Google Chrome. Versions prior to 135.0.7049.52 fail to properly validate untrusted input, allowing a remote attacker to achieve privilege escalation through a crafted HTML page. The flaw is categorized under [CWE-20] Improper Input Validation and [CWE-1287] Improper Validation of Specified Type of Input. Chromium's security team rated the internal severity as Medium.
An attacker exploits the issue by luring a user to a malicious page that abuses the extensions subsystem to perform actions beyond the browser's intended security boundaries.
Critical Impact
Remote attackers can escalate privileges within Chrome by delivering a crafted HTML page to a targeted user, bypassing extension trust boundaries.
Affected Products
- Google Chrome (Desktop) versions prior to 135.0.7049.52
- Chromium-based browsers sharing the vulnerable Extensions code path
- Enterprise Chrome deployments not updated to the Stable channel release from April 2025
Discovery Timeline
- 2025-04-02 - CVE-2025-3070 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-3070
Vulnerability Analysis
The vulnerability resides in Chrome's Extensions subsystem. Chrome's extensions run with elevated privileges relative to standard web content, exposing APIs that ordinary web pages cannot access. When the browser fails to correctly validate untrusted input received from web content interacting with extension surfaces, an attacker can supply malformed or unexpected data to cross that trust boundary.
The issue is tracked as a privilege escalation vector rather than a memory corruption bug. Successful exploitation grants a remote page influence over extension-privileged operations without requiring authentication or user interaction beyond visiting a page.
EPSS data lists a probability of 0.268% at the 18th percentile, indicating low observed exploitation activity to date. No public proof-of-concept or exploit database entry has been released.
Root Cause
The root cause is insufficient validation of untrusted input flowing into extension-related code paths. Under [CWE-1287], the browser accepts data whose type or structure is not verified against expected constraints before privileged actions are performed on it.
Attack Vector
Exploitation is remote and network-based. The attacker hosts a crafted HTML page and induces the victim to load it in an unpatched Chrome build. No prior privileges are required, and the interaction pathway is standard web navigation. The vulnerability manifests in the extensions handling layer described in the Chromium Issue Tracker Entry.
No verified exploit code is publicly available. See the Google Chrome Desktop Update advisory for vendor details.
Detection Methods for CVE-2025-3070
Indicators of Compromise
- Chrome browser processes running versions earlier than 135.0.7049.52 on managed endpoints
- Unexpected installation, enablement, or configuration changes to browser extensions following user navigation to unknown sites
- Outbound connections from chrome.exe child processes to previously unseen domains immediately after page loads
Detection Strategies
- Inventory installed Chrome versions across the fleet and flag hosts below 135.0.7049.52
- Monitor extension manifest changes and new extension installations in user profiles under %LOCALAPPDATA%\Google\Chrome\User Data\Default\Extensions
- Correlate browser telemetry with proxy logs to identify sessions that load unfamiliar HTML content followed by anomalous extension activity
Monitoring Recommendations
- Enable Chrome Enterprise reporting to collect extension inventory and version data centrally
- Alert on Chrome processes spawning unexpected child processes shortly after web navigation events
- Track Group Policy compliance for ExtensionInstallBlocklist and ExtensionInstallAllowlist settings
How to Mitigate CVE-2025-3070
Immediate Actions Required
- Update Google Chrome to version 135.0.7049.52 or later on all Windows, macOS, and Linux endpoints
- Restart Chrome after applying the update to ensure the patched binaries are loaded
- Audit installed extensions and remove any that are unused, unknown, or not sourced from the Chrome Web Store
Patch Information
Google addressed CVE-2025-3070 in the Stable channel release announced on April 1, 2025. Administrators should deploy Chrome 135.0.7049.52 or later. Full release details are available in the Google Chrome Desktop Update advisory, and the underlying tracker record is at the Chromium Issue Tracker Entry.
Workarounds
- Enforce extension allowlisting through enterprise policy to block untrusted third-party extensions
- Restrict browsing to known-good domains via web proxy or DNS filtering until patching completes
- Enable Chrome's Enhanced Safe Browsing to add real-time protection against malicious HTML pages
# Windows Group Policy registry example: allow only vetted extensions
reg add "HKLM\Software\Policies\Google\Chrome\ExtensionInstallAllowlist" /v 1 /t REG_SZ /d "<approved-extension-id>" /f
reg add "HKLM\Software\Policies\Google\Chrome\ExtensionInstallBlocklist" /v 1 /t REG_SZ /d "*" /f
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
