CVE-2026-63127

Summary

The flaw in the rmcp crate's OAuth implementation allows a malicious MCP server to trick a victim into obtaining a legitimate access token, which can then be captured and used by the attacker to impersonate the victim.

Exploitability

Exploitation requires a victim to connect to the malicious server and complete the authorization flow. The attacker must publish metadata for a different legitimate MCP resource.

Blast radius

If exploited, the attacker can impersonate the victim within the token's granted scopes, potentially leading to data breaches or unauthorized access to resources.

Detection

No reliable host or network indicator is derivable from the published description.

Prioritized remediation

Upgrade to version 2.0.0 or later.

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.