The SSL certificate has been signed using a weak hash algorithm - MD5
The remote service uses an SSL certificate that has been signed using a cryptographically weak hashing algorithm - MD5. These algorithms are known to be vulnerable to collision attacks. In theory, a determined attacker may be able to leverage this weakness to generate another certificate with the same digital signature, which could allow him to masquerade as the affected service.
Contact the Certificate Authority to have the certificate reissued.