CVE-2021-42952 in Notebook
Summary
by MITRE • 02/25/2022
Zepl Notebooks before 2021-10-25 are affected by a sandbox escape vulnerability. Upon launching Remote Code Execution from the Notebook, users can then use that to subsequently escape the running context sandbox and proceed to access internal Zepl assets including cloud metadata services.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/06/2026
The vulnerability CVE-2021-42952 represents a critical sandbox escape flaw in Zepl Notebooks versions prior to 2021-10-25, fundamentally undermining the security boundaries designed to isolate user execution environments. This vulnerability resides in the remote code execution capabilities that are inherently part of the notebook interface, creating a dangerous pathway for attackers to bypass the intended security isolation mechanisms. The flaw allows malicious actors to leverage legitimate remote execution features as a stepping stone to break out of the restricted execution environment where notebooks typically operate, thereby accessing resources that should remain isolated from user interaction.
The technical nature of this vulnerability aligns with CWE-749, which describes "Expose of Functionality to Unintended Actors" and represents a direct violation of the principle of least privilege in containerized and sandboxed computing environments. When users execute code within the notebook environment, the system fails to properly enforce boundaries between the user execution context and the underlying infrastructure, creating a pathway for privilege escalation. The sandbox escape occurs through a combination of improper access controls and inadequate isolation mechanisms that allow code executed in one context to gain access to system resources beyond its intended scope.
The operational impact of this vulnerability extends far beyond simple code execution, as it enables attackers to access internal cloud metadata services which typically contain sensitive information including authentication tokens, network configurations, and other system credentials. This access to cloud metadata services represents a severe compromise of the infrastructure's security posture, as such information often provides attackers with additional attack vectors and elevated privileges within the cloud environment. The vulnerability essentially transforms a controlled notebook execution environment into a potential gateway for broader system compromise and data exfiltration.
Organizations utilizing Zepl Notebooks should prioritize immediate remediation through the official patch released on 2021-10-25, which addresses the sandbox escape mechanisms by implementing proper access controls and isolation enforcement. The mitigation strategy should also include network segmentation and monitoring of notebook execution environments to detect anomalous behavior patterns that might indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1078 (Valid Accounts) as attackers could leverage the escape to gain persistent access through metadata service credentials. Additionally, implementing runtime application protection measures and regular security assessments of notebook environments would help prevent similar vulnerabilities from emerging in other collaborative computing platforms.