CVE-2026-87472 in Chrome
Summary
by MITRE • 09/09/2026
Improper input validation in FedCM in Google Chrome prior to 153.0.8010.36 allowed a remote attacker who had compromised the renderer process to spoof UI elements via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as an improper input validation flaw within FedCM in Google Chrome prior to version 153.0.8010.36 represents a significant risk to user interface integrity and trust boundaries within the browser environment. Federated Identity Management, commonly referred to as FedCM, is a critical component that facilitates secure authentication flows between websites and identity providers without exposing sensitive credentials directly to third-party sites. The core technical flaw lies in the insufficient sanitization or validation of input data processed during these federated login interactions. When an attacker crafts a malicious HTML page designed to exploit this specific weakness, they can manipulate how the browser renders elements associated with the authentication dialog. This manipulation allows for UI spoofing, where deceptive interface components are injected or altered to mimic legitimate identity provider prompts. The severity of this issue is classified as Medium by Chromium security standards because it relies on a pre-condition that requires the attacker to have already compromised the renderer process, which significantly limits its exploitability compared to remote code execution vulnerabilities but still poses a serious threat to user trust and data confidentiality if successfully leveraged in conjunction with other attack vectors.
From an operational perspective, this vulnerability enables a sophisticated form of phishing known as UI redressing or clickjacking within the context of authentication flows. An attacker who has achieved renderer process compromise can present users with fake login screens that appear identical to those from trusted identity providers such as Google, Microsoft, or other OAuth2/OIDC compliant services. Users interacting with these spoofed interfaces may inadvertently submit their credentials, session tokens, or personal information directly to the malicious actor rather than the intended service provider. This undermines the fundamental security guarantee of federated authentication, which is that users can trust the interface they are interacting with as a secure channel for credential submission. The impact extends beyond immediate credential theft; it erodes user confidence in browser-based identity management systems and can lead to broader account takeovers if attackers use stolen credentials across multiple platforms where password reuse occurs.
This vulnerability aligns closely with CWE-20, which defines Improper Input Validation, as the root cause is the failure to properly validate data before processing it within the FedCM logic. Furthermore, from a threat modeling perspective using the MITRE ATT&CK framework, this behavior corresponds to techniques such as T1653, which involves Misuse of Trust Relationships, and potentially T1078, Valid Accounts, if the spoofed UI leads to credential harvesting. The attack vector is classified as Remote with Pre-conditions for Privilege Escalation or Process Compromise, indicating that while the initial entry point might be remote via a crafted webpage, the actual exploitation requires a higher level of access within the browser's sandbox architecture. This highlights the importance of defense-in-depth strategies where even if renderer isolation fails, additional safeguards should prevent UI manipulation from succeeding.
Mitigation for this vulnerability primarily involves upgrading Google Chrome to version 153.0.8010.36 or later, which contains patches addressing the input validation logic within FedCM. Organizations and individual users must ensure that browser update policies are enforced to apply security patches promptly upon release. Additionally, implementing strict Content Security Policy directives can help mitigate some aspects of UI spoofing by controlling how resources are loaded and executed on pages. Users should also be educated to verify the URL bar for legitimate identity provider domains before entering sensitive information, although this is a secondary control given that sophisticated attacks may attempt to mask or obfuscate domain indicators. For enterprise environments, deploying endpoint detection and response solutions that monitor renderer process behavior can provide an additional layer of security against exploits that rely on compromising these processes. Regular audits of web applications for proper input handling in authentication flows are also recommended to reduce the attack surface available to adversaries seeking to leverage such browser-side vulnerabilities.