PatchSiren cyber security CVE debrief

CVE-2026-56021 Webmin CVE debrief

CVE-2026-56021 is a medium-severity vulnerability in Webmin that allows unauthenticated attackers to read .conf files within module directories. This issue arises from a bypassable regex pattern. The vulnerability has a CVSS score of 6.9 and is considered medium severity. Webmin users should be aware of this issue and take necessary actions to mitigate it. The CVE was published on June 18, 2026, and no modifications have been made since then. There is no known ransomware campaign use associated with this vulnerability. Users can find more information and potential fixes through the provided resource links.

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, and security teams should be aware of this vulnerability and take necessary actions to mitigate it. This includes reviewing Webmin configurations, updating to the latest version if available, and monitoring for potential exploitation attempts.

Technical summary

The vulnerability CVE-2026-56021 in Webmin allows unauthenticated attackers to read the contents of any file ending in .conf within module directories. This is due to a bypassable regex pattern used in the application. The CVSS score for this vulnerability is 6.9, indicating medium severity. The vulnerability was published on June 18, 2026, and has not been modified since. The CVSS vector is CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/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 the latest version if available.
Review Webmin configurations to ensure they are secure.
Monitor for potential exploitation attempts.
Restrict access to Webmin module directories.
Implement additional security measures such as Web Application Firewalls (WAFs).
Regularly review and update security patches for Webmin.

Evidence notes

The information provided is based on the CVE record and NVD details. The CVE was published on June 18, 2026, and no modifications have been made since then. The vulnerability has a CVSS score of 6.9 and is considered medium severity. The regex pattern used in Webmin can be bypassed, allowing unauthenticated file reads.

Sources and references

Verified primary and authoritative sources

CVE-2026-56021 CVE Program record
Publisher, destination, and source semantics verified

URL: https://www.cve.org/CVERecord?id=CVE-2026-56021

CVE Program - Official CVE Program record with source-provided CVE metadata.
CVE-2026-56021 NVD vulnerability detail
Publisher, destination, and source semantics verified

URL: https://nvd.nist.gov/vuln/detail/CVE-2026-56021

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.