CVE-2026-121222 in Chrome
Summary
by MITRE • 11/03/2026
Incorrect authorization in Forms in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to bypass web origin policy via a crafted HTML page. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an incorrect authorization flaw within the form handling mechanisms of Google Chrome, specifically in versions prior to 157.0.8103.38, represents a significant deviation from expected web origin policy enforcement. This issue stems from a logic error where the browser fails to properly validate or restrict access controls associated with HTML forms when they are embedded within cross-origin contexts. The Chromium project has classified this security incident with a low severity rating, indicating that while the flaw is valid and exploitable under specific conditions, it may not lead directly to high-impact outcomes such as full system compromise without additional vectors. However, even low-severity vulnerabilities in widely deployed browsers can serve as critical stepping stones for more complex attack chains involving social engineering or combined with other weaknesses like cross-site scripting.
At a technical level, the flaw involves the browser's handling of form submissions and their interaction with the same-origin policy. Web origin policies are fundamental security mechanisms that isolate content from different sources to prevent malicious scripts on one page from accessing data on another. In this instance, a crafted HTML page could manipulate form elements or submission behaviors in a way that circumvents these isolation boundaries. By exploiting how Chrome processes authorization checks for forms, an attacker can potentially read sensitive information submitted through forms hosted on a different origin or trigger actions on behalf of the user without proper consent. This bypass allows data to leak across domain boundaries, violating the principle of least privilege and compromising the confidentiality of user interactions with web applications.
The operational impact of this vulnerability is primarily centered around unauthorized access to cross-origin form data and potential state manipulation. An attacker hosting a malicious webpage could craft inputs that trick the victim's browser into submitting forms or revealing input fields in ways that expose sensitive information such as authentication tokens, personal details, or session identifiers to an untrusted third party. This aligns with common attack patterns found in industry standards like CWE-284, which describes improper access control issues where actors are granted privileges they should not have. Furthermore, the exploitation technique relates to ATT&CK tactic TA0001, Initial Access, specifically through techniques that leverage browser vulnerabilities to gain a foothold or exfiltrate data from web sessions. The ability to bypass origin policies undermines trust in the browsing environment and can lead to account takeover if combined with credential harvesting strategies.
Mitigation for this vulnerability requires immediate action by users and administrators relying on affected versions of Google Chrome. The primary remediation step is to update the browser to version 157.0.8103.38 or later, where these authorization checks have been corrected to enforce strict origin boundaries during form processing. Organizations should ensure that endpoint protection policies mandate automatic updates for web browsers to minimize exposure windows. Additionally, users can employ security best practices such as using browser extensions that enhance privacy and block suspicious scripts, although software patching remains the definitive solution. Developers of web applications affected by this flaw may also consider implementing additional server-side validation and CSRF protections to mitigate risks associated with any residual client-side bypasses until all clients are updated.