CVE-2026-46490: samlify: XML Injection in AttributeValue Allows Privilege Escalation in Signed SAML Assertions

Synopsis

XML injection in samlify, a Node.js SAML single sign-on library, allows an authenticated user to embed raw XML markup inside a SAML AttributeValue element. Because samlify does not escape text-node content before the IdP signs the assertion, an attacker can insert additional saml:Attribute elements into the signed payload; the SP then accepts the injected attributes as legitimately signed. Successful exploitation gives the attacker arbitrary role or group membership inside any service provider that uses samlify attributes for authorization. HarborGuard tracks this advisory and will make a patched-image rebuild available the moment an upstream fix version is published.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must reach the SAML authentication endpoint over the network; the library is exposed to any client that can submit a SAML response.

• AuthenticationNot required

  No privileged account is needed; a normal, low-trust user account is sufficient to craft and submit the malicious assertion.

• Victim interactionNot required

  No victim action is required; the attacker submits the crafted SAML response directly to the service provider.

• Attack complexityDetail

  Exploit conditions are straightforward and reliable: no race conditions, memory layout dependencies, or special environmental factors are required to inject the XML markup.

Blast Radius

• The attacker writes arbitrary role and group attributes into the signed SAML assertion, gaining access to application functionality gated behind those roles.
• Any service provider that trusts samlify-validated attributes for authorization decisions accepts the injected claims as legitimate, so the compromise extends to every SP in the federation that shares the same IdP.
• Confidentiality of existing data is not directly affected by this vector; the impact is limited to integrity of the authorization state for the attacker's session.