CVE-2026-56020

Webmin HTTP header authentication bypass

9.2 Critical

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 2.202.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

0.50%Up 0.2 points since Jun 23, 2026

What each source reports

CVE List Score used 9.2

Webmin HTTP header authentication bypass

Record: CVE-2026-56020
CVSS 4.0: 9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-290
Updated: 2026-11-02

EUVDEUVD-2026-37909 9.2

Record: EUVD-2026-37909
CVSS 4.0: 9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-23xj-gfh3-wf2h 9.2

The Webmin HTTP server (miniserv.pl) allows unauthenticated attackers to impersonate any user...

Record: GHSA-23xj-gfh3-wf2h
CVSS 4.0: 9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-290
Updated: 2026-11-02

NVD 9.2

Record: CVE-2026-56020
CVSS 4.0: 9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-290
Updated: 2026-11-02

OSV 9.2

Webmin HTTP header authentication bypass

Record: CVE-2026-56020
CVSS 4.0: 9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness: CWE-290
Updated: 2026-11-02

Affected products

webmin

History

History
Recorded	Changed	Sources
Nov 2, 2026	aliases, published	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-56020 is a critical vulnerability (CVSS 9.2) in Webmin, published June 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.50%, the 42nd percentile. No source names a fixed version.