Webmin accepts basic authentication without session cookies when an attacker provides the 'User-Agent: webmin' header, allowing bypass of additional MFA requirements. Fixed in 2.641.CreditsAdem El Adeb, vulone.com/vul1.comReferenceshttps://webmin.com/security/#webmin-prior-to-2641https://github.com/webmin/webmin/releases/tag/2.641https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-169-02.jsonhttps://www.cve.org/CVERecord?id=CVE-2026-56022
