CVE-2026-121130 in Chrome
Summary
by MITRE • 11/03/2026
Observable discrepancy in Forms in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to obtain sensitive information via a crafted HTML page. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 11/04/2026
The vulnerability identified as an observable discrepancy in form handling within versions of Google Chrome prior to 157.0.8103.38 represents a logic error in how the browser processes and renders HTML forms under specific conditions. This flaw allows a remote attacker, through the delivery of a specially crafted HTML page, to exploit inconsistencies in state management or data binding mechanisms inherent to the rendering engine. The core technical issue stems from an improper handling of form elements where the expected behavior diverges from actual execution when interacting with dynamic content or complex input structures. By leveraging this discrepancy, an attacker can manipulate the browser's internal representation of user inputs, potentially causing sensitive information such as pre-filled credentials, session tokens, or personally identifiable data to be exposed in unintended contexts or accessible via client-side scripts that would otherwise not have access to them.
From a technical perspective, this vulnerability aligns with CWE-200, which categorizes exposure of sensitive information to an unauthorized actor. The attack vector relies on social engineering tactics where the victim is directed to visit a malicious webpage containing crafted HTML code designed to trigger the specific form handling bug. Once triggered, the browser may leak data that was intended for internal processing or restricted fields into observable elements such as console logs, network requests visible via developer tools if misconfigured, or DOM properties accessible to third-party scripts embedded in the page. This type of flaw is particularly dangerous because it does not require a traditional buffer overflow or code execution vulnerability but rather exploits logical assumptions made by the browser engine regarding data isolation and scope within form submissions.
The operational impact of this vulnerability centers on information disclosure that can lead to further compromise scenarios such as session hijacking, credential theft, or targeted phishing campaigns. If an attacker successfully extracts sensitive user data from a victim's active browsing session, they may gain unauthorized access to accounts protected by weak authentication mechanisms or reuse stolen credentials across other services where users have practiced password reuse. Additionally, the leakage of internal application state can aid in crafting more sophisticated attacks against web applications that rely on client-side validation or security checks, as the attacker gains insight into how data is structured and transmitted. Although classified with a low severity rating by Chromium's security team, indicating limited exploitability or narrow impact scope, the cumulative risk remains significant due to the widespread adoption of Chrome and its role in handling sensitive financial and personal transactions.
Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where these form handling discrepancies have been addressed through code refinements that enforce stricter data isolation and validation rules. For organizations unable to immediately patch all endpoints, implementing Content Security Policy headers can help mitigate the impact by restricting script execution sources and preventing unauthorized access to sensitive DOM elements. Furthermore, users should be educated on recognizing suspicious links and avoiding interaction with untrusted web content, particularly those requesting elevated permissions or containing complex form structures. Regular security audits of internal applications that interact heavily with browser forms are also recommended to ensure they do not inadvertently rely on client-side behaviors that could be manipulated by such vulnerabilities. This incident underscores the importance of maintaining up-to-date software environments and adhering to industry standards like OWASP guidelines for secure web application development, which emphasize robust input validation and output encoding to prevent information leakage through UI components.