CVE-2026-74896 in Openssl Encrypt
Summary
by MITRE • 08/17/2026
openssl_encrypt versions before 1.4.0 contain a sandbox escape vulnerability in the DangerousPatternVisitor AST analyzer that fails to detect dunder attribute traversal techniques. Attackers can use __class__, __bases__, __subclasses__(), and __globals__ chains to access restricted functions and execute arbitrary system commands from plugin code.
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Analysis
by VulDB Data Team • 08/17/2026
The OpenSSL Encrypt library, specifically versions prior to 1.4.0, contains a critical sandbox escape vulnerability within its DangerousPatternVisitor abstract syntax tree analyzer component. This flaw stems from an incomplete implementation of security checks designed to restrict the execution capabilities of untrusted plugin code. The primary objective of this sandbox is to prevent malicious or compromised plugins from accessing sensitive system resources and executing arbitrary commands on the host machine. However, the existing detection logic fails to identify specific Python-specific attribute traversal techniques that leverage special methods known as dunder attributes. These include _class_, which provides access to a class's type object; _bases_, which reveals the base classes of an instance; _subclasses_(), which lists all subclasses of a given class; and _globals_, which exposes the global namespace dictionary containing module-level variables and functions.
By chaining these dunder attributes together, an attacker can bypass the intended restrictions of the sandbox environment. For example, starting from a restricted object within the plugin code, one can traverse up to its type via _class_, then access the base classes through _bases_. From there, invoking _subclasses_() allows enumeration of all available subclasses in the Python runtime, including those that inherit from built-in types with dangerous capabilities such as os.system or subprocess.Popen. Finally, accessing _globals_ enables retrieval of references to restricted functions and modules that were previously hidden by the sandbox. This chain effectively neutralizes the protective barriers put in place by the library developers, allowing full access to the underlying operating system environment.
The operational impact of this vulnerability is severe, as it leads directly to arbitrary code execution with the privileges of the process running OpenSSL Encrypt. An attacker who can inject or manipulate plugin inputs can exploit this flaw to execute any command on the host system, potentially leading to complete compromise of the affected server or application infrastructure. This includes data exfiltration, installation of persistent backdoors, lateral movement within a network, and disruption of services. The vulnerability aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command, as it allows external input to influence system-level operations through indirect means rather than direct command injection strings. Furthermore, the exploitation technique maps closely to MITRE ATT&CK techniques related to Defense Evasion and Privilege Escalation, specifically leveraging object attribute discovery and dynamic code execution patterns common in Python environments.
Mitigation for this issue requires an immediate upgrade of OpenSSL Encrypt to version 1.4.0 or later, where the DangerousPatternVisitor has been updated to detect and block these specific dunder-based traversal chains. In addition to upgrading, organizations should implement strict input validation on all plugin code inputs, ensuring that only expected data types and structures are processed by the library. It is also advisable to run applications using least-privilege principles, limiting the permissions of the user account under which OpenSSL Encrypt operates to minimize the potential damage if a sandbox escape occurs. Regular security audits and static analysis tools configured to detect dangerous attribute access patterns in Python code can further reduce the risk surface associated with dynamic plugin execution environments.