CVE-2026-59821: LiteLLM: Custom Code Guardrails production endpoints bypass code safety checks

Should you act?

Normal patch cycle

No exploitation signal; fix it in your next routine update if you are affected. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.9%, percentile 59: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 59% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Needs an account (high (admin)). Exposure depends on who can log in.
• Editorial verdict: Patch this week. LiteLLM Proxy: Three Exploited Flaws in CISA KEV — If you run a self-hosted LiteLLM Proxy older than 1.84.0, upgrade now and treat the provider keys it holds as possibly exposed; SDK-only users are not affected.

What it is

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.82.0-stable, LiteLLM's Custom Code Guardrails production create and update paths did not apply the same sandboxing and validation used by the test endpoint, allowing a privileged user with access to create or update guardrails to submit custom Python code that executed in the LiteLLM proxy environment and could expose secrets available to the process. This issue is fixed in version 1.82.0-stable.

Weakness type: CWE-94.

Product: BerriAI litellm · Assigned by: GitHub_M · Published: 2026-07-08

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: present (depends on deployment conditions)
• Privileges required: high (admin)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 0.90% probability of exploitation activity in the next 30 days; percentile 59.

Timeline

• 2026-07-08 — CVE record published by GitHub_M
• 2026-07-09 — CVE record last updated
• 2026-09-02 — erroneo.us brief: LiteLLM Proxy: Three Exploited Flaws in CISA KEV

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. CVE.org record CVE-2026-59821 cve.org
2. NVD entry CVE-2026-59821 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

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