Authentication Bypass Affecting simplesamlphp/saml2 package, versions <1.10.6 >=2.0, <2.3.8 >=3.0, <3.1.4

simplesamlphp/saml2 is an application written in native PHP that deals with authentication.

Affected versions of this package are vulnerable to Authentication Bypass. An incorrect check of return values in the signature validation utilities allows an attacker to get invalid signatures accepted as valid by forcing an error during validation.

Security Assertion Markup Language (SAML) is an XML-based markup language for security assertions regarding authentication and permissions, most commonly used for single sign-on (SSO) services.

Some XML DOM traversal and canonicalization APIs may be inconsistent in handling of comments within XML nodes. Incorrect use of these APIs by some SAML libraries results in incorrect parsing of the inner text of XML nodes such that any inner text after the comment is lost prior to cryptographically signing the SAML message. Text after the comment therefore has no impact on the signature on the SAML message.

A remote attacker can modify SAML content for a SAML service provider without invalidating the cryptographic signature, which may allow attackers to bypass primary authentication for the affected SAML service provider.

• SimpleSAMLphp Security Advisory
• GitHub Commit