Trustee is a set of tools and components for attesting confidential guests and providing secrets to them. The ART (Attestation Results Token) token, generated by AS, could be manipulated by MITM attacker, but the verifier (CoCo Verification Demander like KBS) could still verify it successfully. In the payload of ART token, the ‘jwk’ could be replaced by attacker with his own pub key. Then attacker can use his own corresponding private key to sign the crafted ART token. Based on current code implementation (v0.8.0), such replacement and modification can not be detected. This issue has been addressed in version 0.8.2 and all users are advised to upgrade. There are no known workarounds for this vulnerability.