CVE-2026-68508 in Hydra
Summary
by MITRE • 08/22/2026
Hydra is a framework for elegantly configuring complex applications. Prior to 1.3.4, hydra.utils.instantiate() resolves and calls Python objects selected by configuration through _resolve_target() in hydra/_internal/instantiate/_instantiate2.py, allowing attacker-controlled target values and arguments to choose dangerous callables. A consuming application, library, CLI workflow, or model loader that passes untrusted configuration, CLI overrides, or model metadata into hydra.utils.instantiate() can therefore execute arbitrary code in its own process, including reading or modifying files and credentials or terminating the process. Version 1.3.4 adds target blocking with an explicit HYDRA_INSTANTIATE_ALLOWLIST_OVERRIDE escape hatch. This issue is fixed in version 1.3.4.
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Analysis
by VulDB Data Team • 08/22/2026
The vulnerability identified in Hydra, a popular framework for configuring complex applications, represents a critical server-side request forgery and arbitrary code execution risk stemming from improper neutralization of special elements used in an object instantiation process. Specifically, the flaw resides within the hydra.utils.instantiate() function prior to version 1.3.4. This utility is designed to resolve Python objects based on configuration data by invoking _resolve_target(). The core technical deficiency lies in the fact that this resolution mechanism does not sufficiently validate or restrict the target classes and their associated arguments when they are derived from untrusted sources such as external configuration files, command-line interface overrides, or model metadata. Consequently, an attacker who can influence these inputs is able to specify dangerous callables within the Python environment where Hydra operates.
From a technical perspective, this vulnerability allows for arbitrary code execution because the instantiate function effectively acts as a dynamic loader that trusts its input without adequate sanitization. When an application passes untrusted configuration into hydra.utils.instantiate(), it inadvertently grants the attacker control over which Python objects are instantiated and how they are called. This capability bypasses standard security boundaries, enabling the execution of arbitrary code within the context of the consuming process. The operational impact is severe, as this can lead to complete system compromise. Attackers may read sensitive files, exfiltrate credentials stored in memory or on disk, modify critical application data, or terminate the service entirely through denial-of-service attacks by invoking destructive methods.
This issue aligns with Common Weakness Enumeration (CWE) categories such as CWE-94 Improper Control of Generation of Code ('Code Injection') and CWE-502 Deserialization of Untrusted Data. The attack vector is consistent with MITRE ATT&CK techniques related to Command and Scripting Interpreter abuse, specifically where an attacker leverages legitimate system utilities or libraries to execute malicious commands under the guise of normal application behavior. In environments using Hydra for model loading in machine learning pipelines or complex CLI workflows, this vulnerability poses a significant risk if third-party models or configurations are ingested without rigorous validation.
The remediation strategy involves upgrading to version 1.3.4 or later, which introduces target blocking mechanisms and an explicit HYDRA_INSTANTIATE_ALLOWLIST_OVERRIDE escape hatch. This fix enforces stricter controls over which classes can be instantiated via the utility function. Organizations relying on Hydra should immediately patch their dependencies to mitigate this risk. Furthermore, developers implementing custom configurations should adhere to the principle of least privilege by ensuring that only trusted and pre-approved configuration sources are passed to instantiation functions. Implementing allowlists for permitted target modules and classes provides a robust defense-in-depth strategy against such injection attacks, ensuring that dynamic code execution remains confined to expected and safe boundaries within the application architecture.