CVE-2026-56020 (GCVE-0-2026-56020)

Vulnerability from cvelistv5 – Published: 2026-06-18 16:12 – Updated: 2026-06-18 16:12
VLAI
Title
Webmin HTTP header authentication bypass
Summary
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.
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
9.2 (Critical)
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
CWE
  • CWE-290 - Authentication Bypass by Spoofing
Assigner
References
Impacted products
Vendor Product Version
Webmin Webmin Affected: 0 , < 2.641 (custom)
Unaffected: 2.641
Create a notification for this product.
Date Public
2026-06-18 00:00
Credits
Adem El Adeb, vulone.com/vul1.com
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unknown",
          "product": "Webmin",
          "vendor": "Webmin",
          "versions": [
            {
              "lessThan": "2.641",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            },
            {
              "status": "unaffected",
              "version": "2.641"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Adem El Adeb, vulone.com/vul1.com"
        }
      ],
      "datePublic": "2026-06-18T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        },
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 9.2,
            "baseSeverity": "CRITICAL",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH"
          }
        },
        {
          "other": {
            "content": {
              "id": "CVE-2026-56020",
              "options": [
                {
                  "Exploitation": "none"
                },
                {
                  "Automatable": "no"
                },
                {
                  "Technical Impact": "total"
                }
              ],
              "role": "CISA Coordinator",
              "timestamp": "2026-05-29T20:04:47.266910Z",
              "version": "2.0.3"
            },
            "type": "ssvc"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-290",
              "description": "CWE-290 Authentication Bypass by Spoofing",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-18T16:12:05.368Z",
        "orgId": "9119a7d8-5eab-497f-8521-727c672e3725",
        "shortName": "cisa-cg"
      },
      "references": [
        {
          "name": "url",
          "tags": [
            "release-notes"
          ],
          "url": "https://github.com/webmin/webmin/releases/tag/2.641"
        },
        {
          "name": "url",
          "tags": [
            "release-notes"
          ],
          "url": "https://webmin.com/security/#webmin-prior-to-2641"
        },
        {
          "name": "url",
          "url": "https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-169-02.json"
        },
        {
          "name": "url",
          "tags": [
            "vdb-entry"
          ],
          "url": "https://www.cve.org/CVERecord?id=CVE-2026-56020"
        }
      ],
      "title": "Webmin HTTP header authentication bypass"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "9119a7d8-5eab-497f-8521-727c672e3725",
    "assignerShortName": "cisa-cg",
    "cveId": "CVE-2026-56020",
    "datePublished": "2026-06-18T16:12:05.368Z",
    "dateReserved": "2026-06-18T14:15:27.103Z",
    "dateUpdated": "2026-06-18T16:12:05.368Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.