CVE-2025-12739 in Looker
Summary
by MITRE • 11/24/2025
An attacker with viewer permissions in Looker could craft a malicious URL that, when opened by a Looker admin, would execute an attacker-supplied script. Exploitation required at least one Looker extension installed on the instance.
Looker-hosted and Self-hosted were found to be vulnerable. This issue has already been mitigated for Looker-hosted instances. No user action is required for these.
Self-hosted instances must be upgraded as soon as possible. This vulnerability has been patched in all supported versions of Self-hosted. The versions below have all been updated to protect from this vulnerability. You can download these versions at the Looker download page https://download.looker.com/ : * 24.18.201+ * 25.0.79+ * 25.6.66+ * 25.12.7+ * 25.16.0+ * 25.18.0+ * 25.20.0+
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Analysis
by VulDB Data Team • 11/24/2025
This vulnerability represents a sophisticated cross-site scripting attack vector that exploits the trust relationship between Looker administrators and viewer users within the platform's extension framework. The flaw allows an attacker with minimal viewer permissions to construct a malicious URL that, when accessed by a Looker administrator, executes arbitrary JavaScript code within the admin's browser context. This type of vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically targeting the execution of malicious scripts in the context of a privileged user. The attack requires the presence of at least one Looker extension installed on the target instance, which serves as the attack surface for the exploitation mechanism.
The technical implementation of this vulnerability leverages the extension architecture's trust model, where extensions are granted elevated privileges that can be abused when malicious URLs are crafted with carefully constructed parameters. When an administrator clicks on the malicious URL, the extension framework processes the request and executes the attacker-supplied script without proper input validation or sanitization. This vulnerability is particularly dangerous because it operates at the browser level, bypassing traditional server-side security controls and directly targeting the administrative interface. The attack chain requires the victim to be an administrator with access to the Looker platform, making it a high-impact privilege escalation vector.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the ability to perform actions that are typically restricted to administrators. This includes accessing sensitive data, modifying configurations, and potentially escalating privileges further within the Looker environment. The vulnerability affects both Looker-hosted and self-hosted instances, though the mitigation approach differs between the two deployment models. The attack vector demonstrates the importance of extension security in modern business intelligence platforms where third-party integrations are common. From an attacker perspective, this vulnerability aligns with techniques described in the ATT&CK framework under the T1059.007 sub-technique for Command and Scripting Interpreter, specifically targeting web-based execution environments.
The mitigation strategy implemented by Looker addresses the root cause through input validation and sanitization of URL parameters within the extension framework. The patched versions demonstrate a comprehensive approach to addressing the vulnerability by updating all supported release branches to prevent malicious script execution. Organizations using self-hosted instances must immediately upgrade to one of the specified patched versions to protect against exploitation. The vulnerability disclosure highlights the critical importance of maintaining up-to-date security patches in enterprise platforms and the need for regular security assessments of extension frameworks. The differential treatment between Looker-hosted and self-hosted instances reflects the company's responsibility for maintaining security in their managed environment versus the shared responsibility model for customer-managed deployments.
The vulnerability serves as a reminder of the inherent risks in extension-based architectures and the critical need for proper security controls around user input processing. The attack scenario demonstrates how seemingly minor permission differences can create significant security risks when combined with extension frameworks. Organizations should implement comprehensive monitoring for unusual URL patterns and extension usage to detect potential exploitation attempts. The patch release strategy shows the importance of maintaining multiple supported release channels to ensure timely security updates across different deployment scenarios. This vulnerability also underscores the necessity of conducting security reviews of extension frameworks and implementing proper input validation controls to prevent similar issues in the future.