CVE-2026-2244 in Vertex AI Workbench
Summary
by MITRE • 02/26/2026
A vulnerability in Google Cloud Vertex AI Workbench from 7/21/2025 to 01/30/2026 allows an attacker to exfiltrate valid Google Cloud access tokens of other users via abuse of a built-in startup script.
All instances after January 30th, 2026 have been patched to protect from this vulnerability. No user action is required for this.
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Analysis
by VulDB Data Team • 02/26/2026
This vulnerability resides within Google Cloud Vertex AI Workbench, a managed machine learning platform that enables users to build, train, and deploy machine learning models within the Google Cloud environment. The flaw manifests in the platform's handling of startup scripts, specifically targeting the security boundaries between user instances and the underlying cloud infrastructure. The vulnerability was active between July 21, 2025, and January 30, 2026, representing a window of approximately seven months during which malicious actors could exploit this weakness to compromise user credentials. The affected system architecture allows for privilege escalation through the manipulation of built-in startup scripts that execute with elevated permissions, creating a critical security gap in the platform's access control mechanisms.
The technical exploitation occurs through the abuse of startup script functionality that Google Cloud Vertex AI Workbench provides to users for initializing their virtual environments. When users create or modify instances within the platform, these startup scripts execute with elevated privileges and can access sensitive system resources including authentication tokens stored in memory or temporary storage locations. Attackers can craft malicious startup scripts that, when executed, read and exfiltrate valid Google Cloud access tokens belonging to other users who have authenticated to the same platform. This represents a sophisticated form of credential theft that bypasses traditional authentication mechanisms and operates at the system level rather than through application-layer attacks. The vulnerability essentially allows for lateral movement and credential harvesting within the Google Cloud environment without requiring traditional authentication bypass techniques.
The operational impact of this vulnerability extends beyond simple credential theft, as compromised access tokens can be used to access any resources accessible to the compromised user accounts. This includes but is not limited to data stored in cloud storage buckets, compute resources, database instances, and other Google Cloud services that the compromised users have permissions to access. The attack vector operates silently in the background, making detection particularly challenging as the malicious scripts appear to be legitimate startup procedures. Organizations using Google Cloud Vertex AI Workbench during the affected period faced potential exposure of sensitive data, unauthorized access to cloud resources, and possible lateral movement within their cloud environments. The vulnerability's impact is amplified by the fact that it affects the platform's core infrastructure rather than individual applications, making it a systemic risk across all affected instances.
The mitigation strategy for this vulnerability involved patching the affected Google Cloud Vertex AI Workbench instances to prevent the abuse of startup script functionality for credential extraction. Google's security team implemented controls that restrict the execution environment of startup scripts and enforce stricter access controls on sensitive system resources. The patch ensures that startup scripts cannot access or read authentication tokens belonging to other users, while maintaining the legitimate functionality of the platform's initialization processes. Organizations do not need to take any action as the patch was automatically deployed to all affected instances. This vulnerability aligns with CWE-284 Access Control Issues, specifically addressing improper access control mechanisms that allow unauthorized access to sensitive resources. From an ATT&CK framework perspective, this represents a technique under T1566 Credential Access and T1078 Valid Accounts, where attackers leverage legitimate access to extract credentials and maintain persistence within cloud environments. The vulnerability also demonstrates characteristics of T1059 Command and Scripting Interpreter, as attackers could execute malicious code through the startup script mechanism. Organizations should continue monitoring their cloud environments for similar patterns and ensure comprehensive logging of startup script activities to detect potential future exploitation attempts.