CVE-2026-128637

Open Redirect in MISP Modules Website Login via Unvalidated next Parameter

The MISP Modules website component contains an open redirect vulnerability in its login endpoint. The /login route accepted a user-supplied next query parameter and passed it directly to Flask's redirect() function without validating the destination. An attacker could craft a URL such as https://victim-host/login?next=https://attacker.example/phish and deliver it to a user (e.g., via email or a lookalike page). After the user successfully authenticated, the application issued a 302 redirect to the attacker-controlled external URL. This enables phishing attacks where a user, believing they are still on the legitimate MISP Modules site, may enter additional credentials or sensitive information on the attacker's page. It can also be used to obscure the true destination of a link, bypassing user trust in the legitimate domain. The vulnerability requires the victim to interact with the crafted URL and complete a login, but no prior authentication or special configuration is needed on the attacker's side. The affected component is the website sub-project of misp-modules, specifically the account blueprint in website/app/account/account.py. No version boundaries are specified in the patch metadata.