An open redirect flaw exists in Rocket.Chat versions before 8.4.0, originating from a SAML endpoint that accepts redirect URLs via parameters without strict validation. The vulnerability allows an attacker to force users to be redirected to arbitrary web addresses, potentially enabling phishing or drive‑by downloads, without granting the attacker code execution or data exfiltration capabilities.

Any Rocket.Chat installation running a version earlier than 8.4.0 is affected. The issue is specific to the Rocket.Chat product provided by the vendor Rocket.Chat.

The vulnerability’s base score of 5.3 indicates moderate risk; the exploit probability is estimated to be below one percent, implying that real‑world exploitation is unlikely. It is not listed in the CISA Known Exploited Vulnerabilities catalog. Attackers can exploit the flaw remotely by crafting a SAML URL that includes a malicious redirect parameter; no special privileges are required to use the endpoint.