The error checking routine used for the C_Verify call on a symmetric verification key in the nCipher PKCS#11 library 1.2.0 and later returns the CKR_OK status even when it detects an invalid signature, which could allow remote attackers to modify or forge messages.
http://www.securityfocus.com/bid/5498
http://www.ncipher.com/support/advisories/advisory5_c_verify.html
http://www.iss.net/security_center/static/9895.php
http://archives.neohapsis.com/archives/bugtraq/2002-08/0172.html