CVE-2026-12773 - Vulnerability Details

- BerriAI litellm MCP Proxy user_api_key_auth_mcp.py UserAPIKeyAuth improper authentication

Description

A weakness has been identified in BerriAI litellm up to 1.59.8. Affected is the function UserAPIKeyAuth of the file litellm/proxy/_experimental/mcp_server/auth/user_api_key_auth_mcp.py of the component MCP Proxy. Executing a manipulation can lead to improper authentication. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure.

Published: 2026-06-21

Score: 6.9 Medium

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

A weakness in BerriAI litellm up to version 1.59.8 enables callers to bypass the authentication logic in the UserAPIKeyAuth routine, allowing an unauthenticated attacker to send requests to the MCP Proxy API without possessing a valid API key. The flaw is rooted in authentication failure (CWE‑287) and a weak key verification mechanism (CWE‑303).

Affected Systems

All instances of BerriAI litellm that include the MCP Proxy component and are running version 1.59.8 or earlier may be affected. The vulnerability resides in the file litellm/proxy/_experimental/mcp_server/auth/user_api_key_auth_mcp.py and thus any environment where that module is active without the fix is exposed.

Risk and Exploitability

The flaw carries a CVSS score of 6.9, indicating a moderate to high impact. The EPSS score is below 1%, suggesting a very low but non-zero probability of exploitation, yet the publicly available exploit raises awareness and potential abuse. The vulnerability is not listed in the CISA KEV catalog, but its remote nature means an attacker can reach the vulnerable endpoint over the internet, craft requests without authentic credentials, and gain unauthorized access to the MCP Proxy service.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

BerriAI

litellm

affected

Version	Status	Constraints
`1.59.0`	affected	—
`1.59.1`	affected	—
`1.59.2`	affected	—
`1.59.3`	affected	—
`1.59.4`	affected	—
`1.59.5`	affected	—
`1.59.6`	affected	—
`1.59.7`	affected	—
`1.59.8`	affected	—

No data.

Vendor Product Confidence Versions

Litellm

95%

Version	Status	Scheme	Platform
`1.59.0`	affected	semver	—
`1.59.1`	affected	semver	—
`1.59.2`	affected	semver	—
`1.59.3`	affected	semver	—
`1.59.4`	affected	semver	—
`1.59.5`	affected	semver	—
`1.59.6`	affected	semver	—
`1.59.7`	affected	semver	—
`1.59.8`	affected	semver	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Contact BerriAI to confirm the availability of a patch or update for litellm versions 1.59.8 and earlier
Restrict inbound traffic to the MCP Proxy endpoint, limiting access to trusted networks or applying firewall rules to block exposure to untrusted sources
Implement an additional layer of API‑key validation within your infrastructure, verifying that incoming keys exist in your authorized key store and have not expired before forwarding requests to the proxy
Maintain an inventory of all litellm deployments and apply ongoing monitoring to detect any abuse of the MCP Proxy endpoint

Generated by OpenCVE AI on June 26, 2026 at 14:30 UTC.

Tracking

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Advisories

No advisories yet.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact Low

Vulnerable System Availability Impact Low

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact Low

Integrity Impact Low

Availability Impact Low

User Interaction None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact Low

Integrity Impact Low

Availability Impact Low

User Interaction None

Access Vector Network

Access Complexity Low

Authentication None

Confidentiality Impact Partial

Integrity Impact Partial

Availability Impact Partial

This CVE is not in the KEV list.

The EPSS score is 0.00612.

Exploitation poc

Automatable yes

Technical Impact partial

References

Link	Providers
https://gist.github.com/YLChen-007/3cfaad10a69d7a15e4d4d458cb53309e
https://nvd.nist.gov/vuln/detail/CVE-2026-12773
https://vuldb.com/cve/CVE-2026-12773
https://vuldb.com/submit/811282
https://vuldb.com/vuln/372515
https://vuldb.com/vuln/372515/cti
https://www.cve.org/CVERecord?id=CVE-2026-12773

History

Fri, 26 Jun 2026 12:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-303
References		https://nvd.nist.gov/vuln/detail/CVE-2026-12773 https://www.cve.org/CVERecord?id=CVE-2026-12773
Metrics	threat_severity `None`	threat_severity `Important`

Mon, 22 Jun 2026 18:30:00 +0000

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Sun, 21 Jun 2026 07:45:00 +0000

Type	Values Removed	Values Added
Description		A weakness has been identified in BerriAI litellm up to 1.59.8. Affected is the function UserAPIKeyAuth of the file litellm/proxy/_experimental/mcp_server/auth/user_api_key_auth_mcp.py of the component MCP Proxy. Executing a manipulation can lead to improper authentication. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure.
Title		BerriAI litellm MCP Proxy user_api_key_auth_mcp.py UserAPIKeyAuth improper authentication
First Time appeared		Litellm Litellm litellm
Weaknesses		CWE-287
CPEs		cpe:2.3:a:litellm:litellm::::::::
Vendors & Products		Litellm Litellm litellm
References		https://gist.github.com/YLChen-007/3cfaad10a69d7a15e4d4d458cb53309e https://vuldb.com/cve/CVE-2026-12773 https://vuldb.com/submit/811282 https://vuldb.com/vuln/372515 https://vuldb.com/vuln/372515/cti
Metrics		cvssV2_0 `{'score': 7.5, 'vector': 'AV:N/AC:L/Au:N/C:P/I:P/A:P/E:POC/RL:ND/RC:UR'}` cvssV3_0 `{'score': 7.3, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R'}` cvssV3_1 `{'score': 7.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:X/RC:R'}` cvssV4_0 `{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P'}`

Subscriptions

Litellm Litellm

MITRE

Status: PUBLISHED

Assigner: VulDB

Published: 2026-06-21T03:15:08.647Z

Updated: 2026-06-30T12:06:53.325Z

Reserved: 2026-06-20T09:26:26.143Z

Link: CVE-2026-12773

Vulnrichment

Updated: 2026-06-30T02:46:35.096Z

NVD

No data.

Redhat

Severity : Important

Publid Date: 2026-06-21T03:15:08Z

Links: CVE-2026-12773 - Bugzilla

OpenCVE Enrichment

Updated: 2026-06-26T14:45:06Z

Weaknesses

CWE-287
Improper Authentication
CWE-303
Incorrect Implementation of Authentication Algorithm

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact Low

Vulnerable System Availability Impact Low

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact Low

Integrity Impact Low

Availability Impact Low

User Interaction None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact Low

Integrity Impact Low

Availability Impact Low

User Interaction None

Access Vector Network

Access Complexity Low

Authentication None

Confidentiality Impact Partial

Integrity Impact Partial

Availability Impact Partial

Exploitation poc

Automatable yes

Technical Impact partial

Subscriptions

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