CISA warns of Google Chromium 0-Day Input Validation Vulnerability Exploited in Attacks

CISA has issued an urgent warning about a critical vulnerability in Google Chromium that threat actors are actively exploiting. 

The vulnerability, designated as CVE-2025-6558, poses a significant security risk to millions of users across multiple web browsers that utilize the Chromium engine.

Key Takeaways
1. Chromium vulnerability enables sandbox escape via malicious HTML
2. Affects all Chromium browsers (Chrome, Edge, Opera).
3. CISA requires patches by August 12, 2025, due to active exploitation.

Improper Input Validation (CVE-2025-6558)

The newly identified vulnerability stems from improper input validation within Chromium’s ANGLE (Almost Native Graphics Layer Engine) and GPU components. 

This technical flaw, classified under Common Weakness Enumeration CWE-20, creates a pathway for remote attackers to potentially execute sophisticated sandbox escape attacks. 

The vulnerability’s severity lies in its ability to allow malicious actors to break free from the browser’s security sandbox through carefully crafted HTML pages, effectively bypassing one of the most fundamental security mechanisms designed to protect users from web-based threats.

Security researchers have identified that the improper input validation occurs when the browser processes specific graphics-related operations, particularly those involving GPU acceleration and ANGLE’s OpenGL ES implementation. 

This creates an attack vector where malicious websites can exploit the validation weakness to gain unauthorized access beyond the browser’s confined execution environment.

The vulnerability’s impact extends far beyond Google Chrome alone, affecting the entire ecosystem of Chromium-based browsers. 

Major browsers including Microsoft Edge and Opera are susceptible to exploitation, given their reliance on the same underlying Chromium codebase. 

This widespread exposure potentially puts hundreds of millions of users at risk across different platforms and operating systems.

The attack methodology involves threat actors hosting malicious websites containing specially crafted HTML pages designed to trigger the input validation flaw. 

Once successful, attackers can leverage the sandbox escape to potentially install malware, steal sensitive data, or establish persistent access to compromised systems. 

Mitigations 

CISA has established a firm remediation deadline of August 12, 2025, following the vulnerability’s addition to their Known Exploited Vulnerabilities catalog on July 22, 2025. 

Organizations must apply vendor-provided mitigations immediately or discontinue use of affected products if patches are unavailable. 

The agency specifically references Binding Operational Directive (BOD) 22-01 guidance for cloud services, emphasizing the critical nature of this security issue.

Google has already begun releasing patches through their stable channel updates, with detailed information available through their Chrome releases blog. 

Users and administrators should prioritize immediate updates to the latest browser versions to protect against ongoing exploitation attempts targeting this critical vulnerability.

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