How severe is CVE-2026-42203?

CVE-2026-42203 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-42203 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42203?

CVE-2026-42203 affects Litellm. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42203?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42203 have an EU (EUVD) identifier?

Yes. CVE-2026-42203 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28502.

When was CVE-2026-42203 published?

CVE-2026-42203 was published on 2026-05-08 and last updated on 2026-06-30.

CVE-2026-42203

CVE-2026-42203 is a high-severity vulnerability in Litellm with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-1336.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v4: 8.6
EPSS exploit prediction: 0% (29th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-28502
Weakness: CWE-1336
Affected product: Litellm
Published: 2026-05-08
Last modified: 2026-06-30

Description

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. From version 1.80.5 to before version 1.83.7, the POST /prompts/test endpoint accepted user-supplied prompt templates and rendered them without sandboxing. A crafted template could run arbitrary code inside the LiteLLM Proxy process. The endpoint only checks that the caller presents a valid proxy API key, so any authenticated user could reach it. Depending on how the proxy is deployed, this could expose secrets in the process environment (such as provider API keys or database credentials) and allow commands to be run on the host. This issue has been patched in version 1.83.7.

Frequently asked questions

What is CVE-2026-42203?: LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. From version 1.80.5 to before version 1.83.7, the POST /prompts/test endpoint accepted user-supplied prompt templates and rendered them without sandboxing. A crafted template could run arbitrary code inside the LiteLLM Proxy process. The endpoint only checks that the caller presents a valid proxy API key, so any authenticated user could reach it. Depending on how the proxy is deployed, this could expose secrets in the process environment (such as provider API keys or database credentials) and allow commands to be run on the host. This issue has been patched in version 1.83.7.
How severe is CVE-2026-42203?: CVE-2026-42203 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-42203 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42203?: CVE-2026-42203 affects Litellm. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42203?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42203 have an EU (EUVD) identifier?: Yes. CVE-2026-42203 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28502.
When was CVE-2026-42203 published?: CVE-2026-42203 was published on 2026-05-08 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:litellm:litellm:*:*:*:*:*:*:*:*

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