FKIE_CVE-2026-100724

Vulnerability from fkie_nvd - Published: 2026-09-27 02:17 - Updated: 2026-09-30 17:32
Severity
5.4 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
Summary
http4k (Maven package org.http4k:http4k-core) before 6.49.0.0, 5.42.0.0 and 4.51.0.0 uses substring (Contains) matching on the Host header by default in reverseProxy() and reverseProxyRouting() when dispatching to configured virtual hosts. If these functions are deployed as a public-facing inbound HTTP handler with two or more configured virtual hosts, a remote attacker can supply a Host header that merely contains a configured vhost name (for example Host: admin.evil.com for a vhost configured as "admin") and be routed to that vhost, bypassing routing-based authorization. The intended outbound-dispatch and test-time uses, where the Host value is set by the calling application, are not affected.
References
disclosure@vulncheck.comhttps://github.com/http4k/http4k/commit/0121b05537
disclosure@vulncheck.comhttps://github.com/http4k/http4k/commit/54c6385615
disclosure@vulncheck.comhttps://github.com/http4k/http4k/security/advisories/GHSA-jrpc-7vxp-69p6
disclosure@vulncheck.comhttps://www.vulncheck.com/advisories/http4k-before-6.49.0.0-host-header-routing-bypass-via-reverseproxy
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:maven/org.http4k/http4k-core",
          "product": "http4k",
          "vendor": "http4k",
          "versions": [
            {
              "lessThan": "6.49.0.0",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            },
            {
              "status": "unaffected",
              "version": "6.49.0.0",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:maven/org.http4k/http4k-core",
          "product": "http4k",
          "vendor": "http4k",
          "versions": [
            {
              "lessThan": "5.42.0.0",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            },
            {
              "status": "unaffected",
              "version": "5.42.0.0",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:maven/org.http4k/http4k-core",
          "product": "http4k",
          "vendor": "http4k",
          "versions": [
            {
              "lessThan": "4.51.0.0",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            },
            {
              "status": "unaffected",
              "version": "4.51.0.0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "disclosure@vulncheck.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "http4k (Maven package org.http4k:http4k-core) before 6.49.0.0, 5.42.0.0 and 4.51.0.0 uses substring (Contains) matching on the Host header by default in reverseProxy() and reverseProxyRouting() when dispatching to configured virtual hosts. If these functions are deployed as a public-facing inbound HTTP handler with two or more configured virtual hosts, a remote attacker can supply a Host header that merely contains a configured vhost name (for example Host: admin.evil.com for a vhost configured as \"admin\") and be routed to that vhost, bypassing routing-based authorization. The intended outbound-dispatch and test-time uses, where the Host value is set by the calling application, are not affected."
    }
  ],
  "id": "CVE-2026-100724",
  "lastModified": "2026-09-30T17:32:07.107",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.4,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 2.7,
        "source": "disclosure@vulncheck.com",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "LOW",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "disclosure@vulncheck.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-100724",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-30T15:15:13.800731Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-27T02:17:20.603",
  "references": [
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/http4k/http4k/commit/0121b05537"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/http4k/http4k/commit/54c6385615"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/http4k/http4k/security/advisories/GHSA-jrpc-7vxp-69p6"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://www.vulncheck.com/advisories/http4k-before-6.49.0.0-host-header-routing-bypass-via-reverseproxy"
    }
  ],
  "sourceIdentifier": "disclosure@vulncheck.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-444"
        }
      ],
      "source": "disclosure@vulncheck.com",
      "type": "Secondary"
    }
  ]
}



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