CVE-2026-40320

The ConformityCheck class in giskard-checks rendered the rule parameter through Jinja2's default Template() constructor. Because the rule string is silently interpreted as a Jinja2 template, a developer may not realize that template expressions embedded in rule definitions are evaluated at runtime. In a scenario where check definitions are loaded from an untrusted source (e.g. a shared project file or externally contributed configuration), this could lead to arbitrary code execution.

giskard-checks is a local developer testing library with no network-facing service. Check definitions, including the rule parameter, are provided in application code or project configuration files and executed locally. Exploitation requires write access to a check definition and subsequent execution of the test suite by a developer.

However, the implicit template evaluation of the rule parameter is not obvious from the API surface. This hidden behavior increases the likelihood of a developer inadvertently passing untrusted input to it when integrating the library into a larger system.

Affected Component

conformity.py, line 59:

from jinja2 import Template
...
formatted_rule = Template(self.rule).render(trace=trace)

Affected Versions

giskard-checks < 1.0.2b1

Patched Version

giskard-checks >= 1.0.2b1 (template parsing removed from rule evaluation entirely)

Credit

Giskard-AI thanks @dhabaleshwar for identifying the unsandboxed template usage.

CVE-2026-40320 has a CVSS score of 7.8 (Medium). 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 (1.0.2b1); upgrading removes the vulnerable code path.

Kodem intelligence

Upgrade to giskard-checks >= 1.0.2b1. The template rendering has been removed from rule evaluation.

1. What is CVE-2026-40320? CVE-2026-40320 is a medium-severity security vulnerability in giskard-checks (pip), affecting versions <= 1.0.1b1. It is fixed in 1.0.2b1.
2. How severe is CVE-2026-40320? CVE-2026-40320 has a CVSS score of 7.8 (Medium). 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.
3. Which versions of giskard-checks are affected by CVE-2026-40320? giskard-checks (pip) versions <= 1.0.1b1 is affected.
4. Is there a fix for CVE-2026-40320? Yes. CVE-2026-40320 is fixed in 1.0.2b1. Upgrade to this version or later.
5. Is CVE-2026-40320 exploitable, and should I be worried? Whether CVE-2026-40320 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
6. What actually determines whether CVE-2026-40320 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.
7. How do I fix CVE-2026-40320? Upgrade giskard-checks to 1.0.2b1 or later.