The XML Signature specification allows for HMAC truncation, which may allow a remote attacker to bypass authentication.
XML Signature Syntax and Processing (XMLDsig) is a W3C recommendation for providing integrity, message authentication, and/or signer authentication services for data. XMLDsig is commonly used by web services such as SOAP. The XMLDsig recommendation includes support for HMAC truncation, as specified in RFC2014. When HMAC truncation is under the control of an attacker, however, this can result in an effective authentication bypass. For example, by specifying an HMACOutputLength of 1, only one bit of the signature is verified. This can allow an attacker to forge an XML signature that will be accepted as valid.
This vulnerability can allow an attacker to bypass the authentication mechanism provided by the XML Signature specification.
No further blocker. Closing this bug.