PT-2026-50711 · Webmin · Webmin

Adem El Adeb · CVE-2026-56020 · Published 2026-06-18 · Updated 2026-06-22

Positive Technologies (AI Summary)

CVSS v4.0

9.2

Critical

Base vector

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

Name of the Vulnerable Software and Affected Versions Webmin versions prior to 2.641

Description The Webmin HTTP server (miniserv.pl) improperly trusts a client-supplied HTTP header for SSL client certificate identity. This allows unauthenticated remote attackers to spoof certificate distinguished names (DNs)—the unique identifiers used in digital certificates—by sending a forged HTTP header. Consequently, an attacker can impersonate any user with a configured SSL client certificate without presenting a valid certificate, leading to a remote authentication bypass and potential full takeover of administrative accounts and managed systems.

Recommendations Upgrade to version 2.641.

Exploit

Fix

Authentication Bypass by Spoofing

Weakness Enumeration

CWE-290

Related Identifiers

CVE-2026-56020

Affected Products

Webmin

References · 12

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56020.json · Exploit
• https://cve.org/CVERecord?id=CVE-2026-56020 · Security Note
• https://osv.dev/vulnerability/CVE-2026-56020 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-56020 · Security Note
• https://github.com/webmin/webmin/releases/tag/2.641 · Note
• https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-169-02.json · Note
• https://t.me/cveNotify/170897 · Telegram Post
• https://webmin.com/security/#webmin-prior-to-2641 · Note
• https://t.me/CVEtracker/57265 · Telegram Post
• https://t.me/cveNotify/171483 · Telegram Post
• https://twitter.com/UpwindMDR/status/2067878349565808757 · Twitter Post
• https://t.me/cveNotify/170642 · Telegram Post