CVE-2026-12773
Description
A flaw was found in BerriAI litellm, within its MCP Proxy component. A remote attacker could exploit an improper authentication vulnerability in the UserAPIKeyAuth function. This could allow unauthorized access, potentially compromising the confidentiality, integrity, and availability of data within the system.
Statement
A flaw was found in litellm. When the LiteLLM proxy MCP authentication flow mishandles 401/403 errors from API key validation, an attacker may bypass MCP proxy authentication and reach backend MCP servers that are configured with allow_all_keys: true. This issue affects litellm versions prior to 1.81.16 as shipped in select Red Hat products.
Mitigation
Upgrade to litellm 1.81.16 or later. As a workaround, do not configure backend MCP servers with allow_all_keys: true, and restrict network access to the LiteLLM MCP proxy endpoints.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.3 | 9.8 | 7.3 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | High | Low |
| Integrity Impact | Low | High | Low |
| Availability Impact | Low | High | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Frequently Asked Questions
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