CVE-2026-56020

Webmin HTTP header authentication bypass

CVSS 9.2 CRITICALEPSS 0.3%CWE-290

The Webmin HTTP server (miniserv.pl) allows unauthenticated attackers to impersonate any user with a configured SSL client certificate by sending a forged HTTP header. A remote attacker can spoof certificate DNs and authenticate as any user. Fixed in 2.641.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Affected products

Webmin · Webmin

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References

https://github.com/webmin/webmin/releases/tag/2.641 https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-169-02.json https://webmin.com/security/#webmin-prior-to-2641 https://www.cve.org/CVERecord?id=CVE-2026-56020