CVE-2026-123271 · AI agents & MCP
NO FIX YET · SEE WHAT TO DO
ChatCLI before v1.215.2 trusts the resource URL that a remote MCP server supplies during its OAuth login flow without checking it against the configured server. A malicious MCP server can get a user's bearer token issued for another resource and then replay that token against it.
first public Oct 11, 2026 · 1 source
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Teams that run ChatCLI and connect it to MCP servers that use OAuth login are exposed, since a malicious or compromised MCP server could collect a token. Installations that do not use MCP OAuth login are not affected by this flaw, as described in the sources.
Not affected if no-mcp-oauth, no-untrusted-mcp-servers
Who cares chatcli, developers, mcp, oauth
v1.215.2.v1.215.2 or later.ChatCLI before v1.215.2 contains an improper validation vulnerability in the MCP OAuth login flow that uses server-supplied Protected Resource Metadata as the resource indicator without checking it matches the configured server URL. A malicious MCP server can declare another resource on the same authorization server, obtain the user's bearer token for it, and replay that token against the other resource.
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