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CVE-2026-56022 Webmin CVE debrief

CVE-2026-56022 is a medium-severity vulnerability in Webmin that allows authentication bypass when a specific 'User-Agent' header is provided. An attacker can bypass additional MFA requirements by providing the 'User-Agent: webmin' header. The vulnerability was fixed in Webmin version 2.641. Users of affected Webmin versions should update to 2.641 or later to mitigate this vulnerability. This vulnerability has a CVSS score of 6.9 and is considered medium severity. Webmin users should review their systems for potential exploitation.

Vendor
Webmin
Product
Unknown
CVSS
MEDIUM 6.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-18
Original CVE updated
2026-08-11
Advisory published
2026-06-18
Advisory updated
2026-08-11

Who should care

Webmin users, administrators of systems using Webmin for management, and security teams responsible for patching and vulnerability management should be aware of this vulnerability.

Technical summary

CVE-2026-56022 is a vulnerability in Webmin that allows for authentication bypass. When an attacker provides the 'User-Agent: webmin' header, Webmin accepts basic authentication without session cookies. This enables attackers to bypass additional MFA requirements. The vulnerability was addressed in Webmin version 2.641. The CVSS vector for this vulnerability is CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/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.

Defensive priority

medium

Recommended defensive actions

  • Update Webmin to version 2.641 or later
  • Review system logs for potential exploitation attempts
  • Implement additional security measures such as IP blocking or rate limiting for authentication attempts
  • Consider enabling session cookies for Webmin
  • Monitor Webmin systems for unusual activity
  • Restrict access to Webmin to trusted IP addresses or networks
  • Enable MFA for all Webmin users

Evidence notes

The information provided is based on data from the National Vulnerability Database (NVD) and other reliable sources. The CVE record and NVD detail pages provide comprehensive information about this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-56022 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-56022

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-56022 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-56022

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://github.com/webmin/webmin/releases/tag/2.641

    9119a7d8-5eab-497f-8521-727c672e3725

  • Source reference

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-169-02.json

    9119a7d8-5eab-497f-8521-727c672e3725

  • Source reference

    Unverified legacy reference

    URL: https://webmin.com/security/

    9119a7d8-5eab-497f-8521-727c672e3725

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.