samlify is a Node.js library for SAML single sign-on. Prior to version 2.13.0, samlify’s template substitution only escapes attribute contexts. Values inserted into element text (e.g., "saml:AttributeValue" (saml:AttributeValue)) are not escaped. A normal user can inject XML markup into an attribute value (e.g., email, name) and add new "saml:Attribute" (saml:Attribute) elements inside the signed assertion. The IdP then signs the tampered assertion and the SP accepts the injected attributes as trusted. This allows privilege escalation when attributes are used for authorization (roles/groups). This issue has been patched in version 2.13.0.