Critical Zero-Day Alert: CVE-2025-4664 Exploits Chrome Token Theft on Linux

 

Critical Chrome zero-day (CVE-2025-4664) exposes Linux systems to token theft & session hijacking. Learn how to patch Debian/Gentoo, block exploits, and secure SSO/cloud credentials before attackers strike. Updated mitigation steps for admins.

A newly discovered zero-day vulnerability (CVE-2025-4664) is actively compromising Chromium-based browsers on Linux systems, putting authentication tokens, session data, and sensitive credentials at risk. Unlike typical exploits, this flaw bypasses referrer policy protections, allowing attackers to hijack browsing sessions silently.

For Linux admins managing Debian, Gentoo, or enterprise environments, this isn’t just another security advisory—it’s a live threat requiring immediate patching. Delaying action risks data breaches, lateral network movement, and systemic compromise.

How CVE-2025-4664 Works: The Exploit Mechanism

The vulnerability stems from Chrome’s mishandling of Link HTTP headers when loading external resources (scripts, images, stylesheets). Under the unsafe-url referrer policy, attackers can:

• Steal session tokens from authenticated users

• Capture browsing histories and credential leaks

• Target Linux servers running Chromium-based apps (e.g., kiosks, dev tools)

Affected Systems & Patch Requirements

Distribution	Vulnerable Versions	Patched Version
Debian Linux	Chromium < 120.0.6099.224	120.0.6099.224+
Gentoo Linux	Chrome < 136.0.7103.113	136.0.7103.113+

Windows and macOS are also vulnerable, but Linux admins face higher stakes due to:

• Server-side Chromium usage (e.g., automated workflows)

• Shared system environments with elevated privileges

• Delayed patch cycles in enterprise deployments

Why Immediate Patching is Non-Negotiable

1. Token Hijacking = Full Account Takeover
   Attackers exploit stolen tokens to bypass MFA, accessing SSO portals, cloud consoles, and internal tools.

2. Linux Systems Are High-Value Targets
   Unpatched servers running Chromium (e.g., CI/CD pipelines, admin panels) expose SSH keys, API tokens, and sudo sessions.

3. No Workarounds Exist
   Unlike other CVEs, this bypasses standard security controls, making patches the only fix.

Action Plan: Mitigate CVE-2025-4664 Now

1. Update Immediately

   bash

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   # Debian/Ubuntu
   sudo apt update && sudo apt upgrade chromium
   # Gentoo
   sudo emerge --sync && emerge -av www-client/chromium

2. Audit Token Usage
   Revoke OAuth tokens, JWT sessions, and cached credentials in affected browsers.

3. Enforce Strict Referrer Policies
   

   Configure .htaccess or NGINX/Apache headers to block unsafe-url leaks:

   nginx

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   add_header Referrer-Policy "strict-origin-when-cross-origin";

Conclusion: Act Now to Secure Your Systems Against CVE-2025-4664

Zero-day vulnerabilities like CVE-2025-4664 are a stark reminder that cybersecurity is a race against time. For Linux admins, the stakes couldn’t be higher—this exploit doesn’t just leak data; it hands attackers the keys to your entire authentication framework.

Key Takeaways:

✅ Patch immediately—Debian and Gentoo users must upgrade Chromium to the latest secure versions.

✅ Rotate all session tokens—Assume any active logins in vulnerable browsers are compromised.

✅ Enforce strict referrer policies—Block unsafe-url to prevent future leaks.

The window to mitigate is closing. Threat actors are already scanning for unpatched systems, and every delay increases exposure. Proactive security isn’t just best practice—it’s the difference between a contained incident and a catastrophic breach.