Summary
LiteLLM: Custom Code Guardrails production endpoints bypass code safety checks
Workarounds
If upgrading is not immediately possible:
- Restrict access to
POST /guardrailsandPUT /guardrails/{guardrail_id}to trusted administrators only. - Ensure
LITELLM_MASTER_KEYis configured. - Avoid enabling Custom Code Guardrails for untrusted users.
Impact
LiteLLM's Custom Code Guardrails production create/update paths did not apply the same sandboxing and validation used by the test endpoint.
A privileged user with access to create or update guardrails could submit custom Python code that executed in the LiteLLM proxy environment. In deployments without a configured master key, callers could be treated as proxy administrators, making this reachable without intended administrative authorization.
This could allow arbitrary code execution in the LiteLLM proxy container and exposure of secrets available to 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.
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.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
The issue is fixed in 1.82.0-stable.
LiteLLM recommend upgrading to 1.82.0-stable or later.
Frequently Asked Questions
- What is CVE-2026-59821? CVE-2026-59821 is a low-severity code injection vulnerability in litellm (pip), affecting versions < 1.82.0. It is fixed in 1.82.0. Untrusted input is evaluated as executable code within the application's runtime environment.
- Which versions of litellm are affected by CVE-2026-59821? litellm (pip) versions < 1.82.0 is affected.
- Is there a fix for CVE-2026-59821? Yes. CVE-2026-59821 is fixed in 1.82.0. Upgrade to this version or later.
- Is CVE-2026-59821 exploitable, and should I be worried? Whether CVE-2026-59821 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-2026-59821 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-2026-59821? Upgrade
litellmto 1.82.0 or later.