CVE-2026-77516 describes an authorization bypass in 1Panel-dev's MaxKB versions 2.0.0 through 2.9.2. The flaw allows a lowest-role workspace member, who should be denied access to specific tools, to execute those tools by binding their identifiers through tool_ids, skill_tool_ids, or mcp_tool_ids parameters and invoking execution via the agent or workflow dispatch path. This dispatch path fails to reapply per-tool access controls enforced by dedicated routes. As a result, unauthorized users can execute tools and decrypt server-side initialization parameters, gaining access to credentials carried by the denied tool. No patch or fixed version is available as of the latest review.

Unauthorized users with minimal workspace roles can bypass access controls to execute restricted tools and obtain sensitive credentials embedded in server-side initialization parameters. This leads to confidentiality breaches of credentials and potentially other sensitive data. The vulnerability does not affect availability but impacts confidentiality and integrity to a limited extent. The CVSS 3.1 base score is 5.4 (medium severity), reflecting network attack vector, low attack complexity, low privileges required, no user interaction, and partial confidentiality and integrity impact.

No official fix or patch is currently available for this vulnerability. Users should monitor the vendor's advisories for updates and consider restricting workspace member roles or limiting tool usage until a fix is released. Avoid using affected versions in sensitive environments where unauthorized tool execution could lead to credential exposure.