CVE-2025-5256: URL Redirection to Untrusted Site

SummaryThis advisory addresses an Open Redirection vulnerability in Mautic's user unlocking endpoint. This vulnerability could be exploited by an attacker to redirect legitimate users to malicious websites, potentially leading to phishing attacks or the delivery of exploit kits.

Open Redirection via returnUrl Parameter: An Open Redirection vulnerability exists in the /s/action/unlock/user.user/0 endpoint. The returnUrl parameter, intended for post-action redirection, is not properly validated. This allows an attacker to craft a URL that, when clicked by a user, redirects them to an arbitrary external website controlled by the attacker.

MitigationUpdate Mautic to a version that properly validates or sanitizes the returnUrl parameter to ensure that redirects only occur to trusted, internal URLs or explicitly whitelisted domains.