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CVE-2026-59822— LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback

Quick assessment

Affected
BerriAI litellm
Exploitation
Confirmed exploitation in the wild; remediate immediately
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

LiteLLM是LiteLLM团队开源的一个应用程序。 LiteLLM 1.84.0之前版本存在授权问题漏洞，该漏洞源于MCP Streamable HTTP端点允许未经身份验证的攻击者使用伪造的Authorization标头触发OAuth2直通回退路径，导致LiteLLM密钥验证失败并返回空的UserAPIKeyAuth()对象，从而允许无有效密钥的请求访问MCP工具。

CVSS 8.8 · High KEV EPSS 0.84% · P56

Possible ATT&CK Techniques 1 AI

T1078 · Valid Accounts

Affected Version Matrix 1

VendorProduct Version RangeStatus
BerriAI litellm < 1.84.0 affected
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I. Basic Information for CVE-2026-59822

Vulnerability Information
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Vulnerability Title
LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback
Source: CVE Program / CVE List V5
Vulnerability Description
LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, LiteLLM's MCP Streamable HTTP endpoint allowed an unauthenticated attacker to use a fabricated Authorization header to trigger an OAuth2 passthrough fallback path that replaced failed LiteLLM key validation with an empty UserAPIKeyAuth() object, allowing requests to reach MCP tooling without a valid LiteLLM key. This issue is fixed in version 1.84.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
LiteLLM 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
LiteLLM是LiteLLM团队开源的一个应用程序。 LiteLLM 1.84.0之前版本存在授权问题漏洞，该漏洞源于MCP Streamable HTTP端点允许未经身份验证的攻击者使用伪造的Authorization标头触发OAuth2直通回退路径，导致LiteLLM密钥验证失败并返回空的UserAPIKeyAuth()对象，从而允许无有效密钥的请求访问MCP工具。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
BerriAI litellm < 1.84.0 -

II. Public POCs for CVE-2026-59822

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III. Intelligence Information for CVE-2026-59822

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Patches & Fixes for CVE-2026-59822 (3)

Vendor Advisories for CVE-2026-59822 (1)

Same Patch Batch · BerriAI · 2026-07-08 · 4 CVEs total

CVE-2026-59820 LiteLLM: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CVE-2026-59821 LiteLLM: Custom Code Guardrails production endpoints bypass code safety checks
CVE-2026-59819 LiteLLM: Local file read via request-supplied OIDC file references

IV. Related Vulnerabilities

Same product: litellm
Same vendor: BerriAI
Same weakness: CWE-287

V. Comments for CVE-2026-59822

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