CVE-2026-77519

Deferred Deferred - Pending Action

Authentication Bypass in MaxKB via Expired API Key

Publication date: 2026-09-21

Last updated on: 2026-09-21

Assigner: GitHub, Inc.

Description

MaxKB is an open-source AI assistant for enterprise. In 2.10.2-lts and earlier, the /chat/api/mcp authentication path looks up an ApplicationApiKey using only its secret and active status, without enforcing the is_permanent and expire_time checks used by the standard chat API. A previously valid, non-permanent application key that remains active after expiration can initialize the MCP endpoint, list the published application's tool metadata, invoke tools/call, and create durable application_chat and application_chat_record state even though /chat/api/open rejects the same key. No fixed version is available as of this review.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-21

Last Modified

2026-09-21

Generated

2026-09-22

AI Q&A

2026-09-22

EPSS Evaluated

N/A

NVD

CVE-2026-77519

Affected Vendors & Products

Vendor	Product	Version / Range
maxkb	maxkb	to 2.10.2-lts (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-613	According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization."

Attack-Flow Graph

Executive Summary

This vulnerability is in MaxKB, an open-source AI assistant for enterprises. In versions 2.10.2-lts and earlier, the /chat/api/mcp authentication path checks only the secret and active status of an ApplicationApiKey. It fails to enforce is_permanent and expire_time checks that are used by the standard chat API. This allows a previously valid but expired non-permanent key to still access the MCP endpoint, list tool metadata, invoke tools, and create state even though the standard chat API would reject the same key.

Impact Analysis

An attacker with access to an expired but active non-permanent ApplicationApiKey could exploit this to interact with the MCP endpoint, list tools, invoke functions, and create persistent state. This could lead to unauthorized data access, manipulation, or service disruption within the MaxKB system.

Compliance Impact

The vulnerability allows unauthorized access to AI tool metadata and state management via expired or non-permanent application keys, which could lead to data exposure or unauthorized processing. This may violate GDPR's principles of data minimization and security, and HIPAA's requirements for access controls and integrity, depending on how MaxKB handles sensitive data.

Mitigation Strategies

Review and revoke all non-permanent application API keys in MaxKB 2.10.2-lts or earlier. Ensure only permanent keys with valid expire_time are active. Monitor for unauthorized MCP endpoint access or tool invocations.

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