Threats tagged 'ghsa-h3x9-8c36-m89w'

Mark3labs mcp-go versions before v1.2.1 have an improper validation vulnerability in the OAuthHandler.fetchServerMetadata function. This flaw allows malicious MCP servers to manipulate OAuth token issuance by declaring arbitrary resources in well-known metadata. Attackers can specify a different MCP server as the RFC 8707 resource indicator, causing the authorization server to mint tokens that the attacker can replay against that resource. This vulnerability has a high severity rating with a CVSS score of 8.0.