CVE-2026-54588: Poweradmin has Host Header Injection in OIDC redirect_uri, SAML ACS/SLO URL, and Logout Redirect Construction.

Poweradmin v4.3.2 uses the attacker-controlled HTTP_HOST request header as the authoritative source for building callback URLs in its OIDC, SAML, and logout authentication flows without any validation. An unauthenticated attacker can poison the redirect_uri sent to the Identity Provider, causing the IdP to redirect the victim’s authorization code to an attacker-controlled server - resulting in full account takeover with no credentials required.

Three independent code paths are affected:

• Primary (Critical): OidcService::getCallbackUrl() - redirect_uri poisoning
• Secondary (High): SamlConfigurationService::getBaseUrl() - SAML ACS/SLO URL poisoning
• Tertiary (Medium): LogoutController::getBaseUrl() - post-logout redirect poisoning