Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:NSummary
CVE-2025-6556 is a medium-severity Authentication Bypass Using an Alternate Path or Channel (CWE-288) vulnerability in Google Chrome. Its CVSS base score is 5.4 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-2 (Flaw Remediation) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-19072
Vulnerability Data
Insufficient policy enforcement in Loader in Google Chrome prior to 138.0.7204.49 allowed a remote attacker to bypass content security policy via a crafted HTML page. (Chromium security severity: Low)
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The CVE describes a content security policy bypass in Chrome's Loader via a crafted HTML page, which aligns with Drive-by Compromise (T1189) where an adversary delivers malicious content through a web page to exploit browser weaknesses.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly addresses the Chrome loader flaw by requiring timely application of the vendor patch that corrects the insufficient CSP enforcement.
Enforces information flow policies at external boundaries or proxies, compensating for the browser's CSP bypass by blocking unauthorized resource loads.
Enables monitoring of web content and script execution anomalies that would indicate successful CSP bypass attempts via crafted HTML.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Requiring authentication on every channel and path directly eliminates alternate-path bypasses.
Enforcing authorizations and least privilege across all access vectors prevents unauthenticated alternate paths.
Protecting networks and environments from unauthorized logical access blocks bypass via undocumented channels.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect alternate-path bypasses but does not prevent them in production.
Secure authentication control directly mitigates bypass by requiring strong, consistent authentication on all paths.
Access control policy directly addresses alternate authentication paths by requiring all channels to enforce authentication.
Authentication information management ensures credentials and mechanisms are consistently applied across all access paths.
Access rights provisioning and review prevent bypass via unmonitored or alternate channels.
Privileged access rights control reduces risk of bypass through elevated or alternate paths.