CVE-2026-59822
HighCVSS 8.2Exploitation Probability (EPSS)
Low risk42th percentile - higher than 42% of all known CVEs
Summary
LiteLLM before version 1.84.0 has a vulnerability in the MCP Streamable HTTP endpoint that allows an unauthenticated attacker to bypass LiteLLM key validation using a crafted Authorization header. The attacker can exploit the OAuth2 passthrough fallback path to replace failed key validation with an empty UserAPIKeyAuth() object, allowing requests to reach MCP tooling without a valid key.
Risk Assessment
The risk is unauthorized access to MCP tooling, potentially leading to data leakage, unauthorized use of AI models, or other resources protected by LiteLLM.
Recommendation
Immediately upgrade LiteLLM to version 1.84.0 or later, which contains the fix for this vulnerability.
Other vulnerabilities in LiteLLM
See all- CVE-2026-30623Critical
LiteLLM 1.18.10 contains a remote code execution vulnerability in its MCP server creation functionality. The application allows users to add MCP servers via a JSON configuration specifying arbitrary command and args values, which are executed on the host without validation. This enables attackers to run arbitrary operating system commands.
- CVE-2026-49468Critical
LiteLLM proxy before version 1.84.0 has a Host-header parsing flaw that, under specific conditions, allows unauthenticated access to protected management routes. The issue arises from a mismatch between the route evaluated by the auth layer and the route actually dispatched by FastAPI.
- CVE-2026-42271HighActively exploited
LiteLLM versions 1.74.2 through 1.83.6 have a vulnerability in the POST /mcp-rest/test/connection and POST /mcp-rest/test/tools/list endpoints, which accept a full MCP server configuration including commands to execute. An authenticated user with any API key can run arbitrary commands on the proxy host.
- CVE-2026-42208CriticalActively exploited
In LiteLLM versions from 1.81.16 to before 1.83.7, a database query used during proxy API key checks is vulnerable to SQL injection due to mixing caller-supplied key value into the query text. An unauthenticated attacker can send a crafted Authorization header to any LLM API route, leading to reading and potentially modifying data in the proxy's database.
- CVE-2026-40217High
A vulnerability in LiteLLM through 2026-04-08 allows remote attackers to execute arbitrary code via bytecode rewriting at the /guardrails/test_custom_code URI.
- CVE-2026-35030Critical
In LiteLLM prior to 1.83.0, when JWT authentication is enabled (enable_jwt_auth: true), the OIDC userinfo cache uses the first 20 characters of the token as the cache key. JWT tokens produced by the same signing algorithm have identical first 20 characters, allowing an unauthenticated attacker to craft a token matching the cache and inherit a legitimate user's identity and permissions.
- CVE-2026-35029High
LiteLLM before version 1.83.0 has a vulnerability where the /config/update endpoint does not enforce admin role authorization. An authenticated user can modify proxy configuration, environment variables, and register custom pass-through endpoint handlers, leading to remote code execution, arbitrary file reading, and takeover of privileged accounts.
- CVE-2026-37004Low risk· EPSS 16%
BerriAI litellm <=1.82.4 is vulnerable to Server-Side Template Injection (SSTI), allowing unauthenticated remote attackers to execute arbitrary OS commands via a crafted dotprompt_content parameter in the /prompts/test endpoint due to use of an unsandboxed jinja2.Environment.
- CVE-2026-59821High
LiteLLM prior to version 1.82.0-stable did not apply proper sandboxing and validation for Custom Code Guardrails during creation and update, allowing a privileged user to execute arbitrary Python code in the proxy environment and potentially expose process secrets.
- CVE-2026-59820Medium
LiteLLM before version 1.83.7-stable has a vulnerability due to insufficient file path validation when extracting Skills ZIP archives. An authenticated user with access to LLM API routes or a key with /v1/skills, anthropic_routes, or llm_api_routes can upload a crafted archive that writes files outside the intended directory (path traversal).
Original NVD description (English source)
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.

