Vulnerabilities in QuickCMS software

CERT Polska has received a report about vulnerabilities in QuickCMS software and participated in coordination of their disclosure.

The vulnerabilityCVE-2026-33384: QuickCMS allows a user's session identifier to be set before authentication. The value of this session ID stays the same after authentication. This behaviour enables an attacker to fix a session ID for a victim and later hijack the authenticated session.

The vulnerabilityCVE-2026-33386: QuickCMS is vulnerable to Cross-Site Scripting (XSS) through its insecure HTTP-based plugin‑fetching mechanism. A malicious attacker can perform a Man‑in‑the‑Middle (MITM) attack by impersonating the opensolution.org server and serving arbitrary HTML or JavaScript at the plugin list endpoint. When a user accesses the plugin page, the malicious content is automatically fetched, rendered, and executed.

These issues were fixed in a patch to version 6.8 published on 15.05.2026, deployments without this patch are still vulnerable.

We thank Jakub Lipiński for the responsible vulnerability report.