CVE-2026-63438 (GCVE-0-2026-63438)

Vulnerability from cvelistv5 – Published: 2026-11-06 20:20 – Updated: 2026-11-06 20:20
VLAI
Title
2FAuth: Reverse Proxy Guard Auto-Creates Users With Admin Promotion From Unauthenticated Header Value
Summary
2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Prior to 8.0.0, when AUTHENTICATION_GUARD=reverse-proxy-guard accepts authentication headers from a client that did not pass through a trusted proxy, RemoteUserProvider::retrieveById() creates an account for an unknown REMOTE_USER, promotes the first created account to administrator, and synchronizes the account email from the configured mail header. An unauthenticated remote client can therefore create an administrator on a fresh instance or impersonate and redirect email for a known account, exposing 2FA secrets and administrative functions. This issue is fixed in version 8.0.0.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
  • CWE-287 - Improper Authentication
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7993 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Bubka 2FAuth Affected: < 8.0.0
guessed Create a notification for this product.
Show details on NVD website
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "2FAuth",
          "vendor": "Bubka",
          "versions": [
            {
              "status": "affected",
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            }
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          "value": "2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Prior to 8.0.0, when AUTHENTICATION_GUARD=reverse-proxy-guard accepts authentication headers from a client that did not pass through a trusted proxy, RemoteUserProvider::retrieveById() creates an account for an unknown REMOTE_USER, promotes the first created account to administrator, and synchronizes the account email from the configured mail header. An unauthenticated remote client can therefore create an administrator on a fresh instance or impersonate and redirect email for a known account, exposing 2FA secrets and administrative functions. This issue is fixed in version 8.0.0."
        }
      ],
      "metrics": [
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            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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      "providerMetadata": {
        "dateUpdated": "2026-11-06T20:20:27.407Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
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          "name": "https://github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24"
        },
        {
          "name": "https://github.com/Bubka/2FAuth/commit/43873cbfba445926c7008b4291eeee67752af9e8",
          "tags": [
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          "url": "https://github.com/Bubka/2FAuth/commit/43873cbfba445926c7008b4291eeee67752af9e8"
        },
        {
          "name": "https://github.com/Bubka/2FAuth/commit/8a4c395cac97f8b70b4a822639a6ad8a816f927c",
          "tags": [
            "x_refsource_MISC"
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        },
        {
          "name": "https://github.com/Bubka/2FAuth/commit/d9e58ac4a63fbd8a073e423567881c81a87915de",
          "tags": [
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          "url": "https://github.com/Bubka/2FAuth/commit/d9e58ac4a63fbd8a073e423567881c81a87915de"
        },
        {
          "name": "https://github.com/Bubka/2FAuth/releases/tag/v8.0.0",
          "tags": [
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        }
      ],
      "source": {
        "advisory": "GHSA-r9xx-45m8-mw24",
        "discovery": "UNKNOWN"
      },
      "title": "2FAuth: Reverse Proxy Guard Auto-Creates Users With Admin Promotion From Unauthenticated Header Value"
    }
  },
  "cveMetadata": {
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    "cveId": "CVE-2026-63438",
    "datePublished": "2026-11-06T20:20:27.407Z",
    "dateReserved": "2026-07-16T19:35:57.767Z",
    "dateUpdated": "2026-11-06T20:20:27.407Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-11-07",
      "epss": "0.00505",
      "percentile": "0.43411"
    },
    "nvd": {
      "cve": {
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          {
            "affectedData": [
              {
                "product": "2FAuth",
                "vendor": "Bubka",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 8.0.0"
                  }
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            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Prior to 8.0.0, when AUTHENTICATION_GUARD=reverse-proxy-guard accepts authentication headers from a client that did not pass through a trusted proxy, RemoteUserProvider::retrieveById() creates an account for an unknown REMOTE_USER, promotes the first created account to administrator, and synchronizes the account email from the configured mail header. An unauthenticated remote client can therefore create an administrator on a fresh instance or impersonate and redirect email for a known account, exposing 2FA secrets and administrative functions. This issue is fixed in version 8.0.0."
          }
        ],
        "id": "CVE-2026-63438",
        "lastModified": "2026-11-06T21:17:09.770",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
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                "baseSeverity": "CRITICAL",
                "confidentialityImpact": "HIGH",
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                "scope": "UNCHANGED",
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                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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        "published": "2026-11-06T21:17:09.770",
        "references": [
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            "url": "https://github.com/Bubka/2FAuth/commit/43873cbfba445926c7008b4291eeee67752af9e8"
          },
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            "source": "security-advisories@github.com",
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            "url": "https://github.com/Bubka/2FAuth/releases/tag/v8.0.0"
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          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24"
          }
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        "vulnStatus": "Received",
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              }
            ],
            "source": "security-advisories@github.com",
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          }
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      }
    }
  }
}



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