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CVE-2025-4600

Status: AnalyzedHigh (8.7)—

A request smuggling vulnerability existed in the Google Cloud Classic Application Load Balancer due to improper handling of chunked-encoded HTTP requests. This allowed attackers to craft requests that could be misinterpreted by backend servers. The issue was fixed by disallowing stray data after a chunk, and is no longer exploitable. No action is required as Classic Application Load Balancer service after 2025-04-26 is not vulnerable.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

Vulnerabilidad de request smuggling (CWE-444) en load balancer expuesto en red sin autenticación (AV:N/PR:N) explotable remotamente. Permite manipulación de peticiones hacia servidores backend y acceso no autorizado a flujos web.

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Vulnerability ScanningPrivileged Account ManagementNetwork SegmentationNetwork Intrusion PreventionLimit Access to Resource Over NetworkFilter Network Traffic

Affected technologies (1)

Google — Application Load Balancer

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2025-4600",
  "cveTags": [
    {
      "tags": [
        "exclusively-hosted-service"
      ],
      "sourceIdentifier": "cve-coordination@google.com"
    }
  ],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2025-4600",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2025-05-16T14:54:15.295181Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "cve-coordination@google.com",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 8.7,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:L/SI:L/SA:L/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",
          "exploitMaturity": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "subIntegrityImpact": "LOW",
          "vulnIntegrityImpact": "HIGH",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "LOW",
          "vulnAvailabilityImpact": "NONE",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "LOW",
          "vulnConfidentialityImpact": "NONE",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
      }
    ]
  },
  "affected": [
    {
      "source": "cve-coordination@google.com",
      "affectedData": [
        {
          "vendor": "Google Cloud",
          "product": "Classic Application Load Balancer",
          "versions": [
            {
              "status": "affected",
              "version": "0"
            }
          ],
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2025-05-16T14:15:32.580",
  "references": [
    {
      "url": "https://cloud.google.com/support/bulletins#gcp-2025-027",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "cve-coordination@google.com"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "cve-coordination@google.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-444"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "A request smuggling vulnerability existed in the Google Cloud Classic Application Load Balancer due to improper handling of chunked-encoded HTTP requests. This allowed attackers to craft requests that could be misinterpreted by backend servers. The issue was fixed by disallowing stray data after a chunk, and is no longer exploitable. No action is required as Classic Application Load Balancer service after 2025-04-26 is not vulnerable."
    },
    {
      "lang": "es",
      "value": "Existía una vulnerabilidad de contrabando de solicitudes en Google Cloud Classic Application Load Balancer debido a la gestión incorrecta de solicitudes HTTP con codificación fragmentada. Esto permitía a los atacantes manipular solicitudes que los servidores backend podían malinterpretar. El problema se solucionó deshabilitando los datos dispersos después de un fragmento y ya no es explotable. No se requiere ninguna acción, ya que el servicio del balanceador de carga de aplicaciones clásico después del 26/04/2025 no es vulnerable."
    }
  ],
  "lastModified": "2026-06-17T09:33:36.230",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:google:application_load_balancer:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "E79FC0BE-EAA0-48C0-81FF-9B6C24A28DA4",
              "versionEndExcluding": "2025-04-26"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve-coordination@google.com"
}