Summary
Hydra: hydra.utils.instantiate with untrusted config can lead to code execution
hydra.utils.instantiate() resolves and calls Python objects from config. If an
application passes untrusted config to instantiate(), an attacker who controls_target_ and its arguments can cause arbitrary code execution in the consuming
process.
Hydra is not a network service. Exploitation requires a consuming application,
library, or user workflow to load attacker-controlled config, CLI overrides, or
model metadata and pass it to hydra.utils.instantiate().
Details
Hydra's instantiate API is designed to construct objects and call functions from
configuration. For example:
component:
_target_: package.module.Class
arg: value
When this config is passed to hydra.utils.instantiate(), Hydra resolves_target_ and calls it with the provided arguments.
This is intended for trusted application configuration. However, if untrusted
input controls _target_, the config becomes a callable-selection mechanism. A
malicious config can select a callable capable of executing code or commands and
provide attacker-controlled arguments.
This issue is the same general class of problem discussed by Unit 42 for
downstream AI/ML libraries such as NVIDIA NeMo, where untrusted model metadata
was passed into Hydra instantiate:
https://unit42.paloaltonetworks.com/rce-vulnerabilities-in-ai-python-libraries/
Hydra 1.3.4 includes a blacklist for some dangerous _target_ values. That
blacklist is defense-in-depth and is not a complete security boundary. The
blacklist is not present in the released hydra-core 1.3.3 package, so this
issue should not be described as a bypass of a released 1.3.3 blacklist.
Affected Usage
Applications and libraries are affected when they pass untrusted or semi-trusted
config, model metadata, CLI overrides, or other externally controlled data tohydra.utils.instantiate() without constraining which targets may be
instantiated.
Trusted application-owned configuration is not affected in the same way.
Impact
A successful attack can execute code in the process that callshydra.utils.instantiate(). The impact is limited to the privileges and
environment of that process.
Potential impact includes:
- Reading files, credentials, environment variables, or data accessible to the
process - Modifying files, outputs, checkpoints, or application state writable by the
process - Terminating or disrupting the process
Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.
CVE-2026-68508 has a CVSS score of 7.8 (High). The vector is requires local access, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.3.4); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Hydra 1.3.4 hardens the existing behavior by adding a blacklist of obvious
dangerous targets. It is a substantial security improvement, and users remaining
on the 1.3 release line should upgrade to 1.3.4 or a newer version.
The unreleased Hydra 1.4 development line uses an allowlist-based instantiation
model that fully addresses this vulnerability class. The allowlist must come
from trusted application code or another trusted channel, not from the untrusted
config being instantiated.
Applications that consume untrusted or semi-trusted config should not pass it
directly to hydra.utils.instantiate(). They should validate _target_ values
against a trusted allowlist before instantiation.
Frequently Asked Questions
- What is CVE-2026-68508? CVE-2026-68508 is a high-severity code injection vulnerability in hydra-core (pip), affecting versions <= 1.3.3. It is fixed in 1.3.4. Untrusted input is evaluated as executable code within the application's runtime environment.
- How severe is CVE-2026-68508? CVE-2026-68508 has a CVSS score of 7.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of hydra-core are affected by CVE-2026-68508? hydra-core (pip) versions <= 1.3.3 is affected.
- Is there a fix for CVE-2026-68508? Yes. CVE-2026-68508 is fixed in 1.3.4. Upgrade to this version or later.
- Is CVE-2026-68508 exploitable, and should I be worried? Whether CVE-2026-68508 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-68508 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-68508? Upgrade
hydra-coreto 1.3.4 or later.