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CVE-2018-6335

Status: ModifiedHigh (7.5)—

A Malformed h2 frame can cause 'std::out_of_range' exception when parsing priority meta data. This behavior can lead to denial-of-service. This affects all supported versions of HHVM (3.25.2, 3.24.6, and 3.21.10 and below) when using the proxygen server to handle HTTP2 requests.

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).

Affected technologies (1)

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2018-6335",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2018-6335",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2025-05-06T19:01:52.053278Z"
        }
      }
    ],
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 5,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:N/I:N/A:P",
          "authentication": "NONE",
          "integrityImpact": "NONE",
          "accessComplexity": "LOW",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV30": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.0",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
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          "version": "3.1",
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          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "cve-assign@fb.com",
      "affectedData": [
        {
          "vendor": "Facebook",
          "product": "HHVM",
          "versions": [
            {
              "status": "affected",
              "version": "3.25.3"
            },
            {
              "status": "affected",
              "version": "3.25.0"
            },
            {
              "status": "affected",
              "version": "3.24.7"
            },
            {
              "status": "affected",
              "version": "3.22.0"
            },
            {
              "status": "affected",
              "version": "3.21.11"
            },
            {
              "status": "affected",
              "version": "unspecified",
              "lessThan": "3.21.11",
              "versionType": "custom"
            }
          ]
        }
      ]
    }
  ],
  "published": "2018-12-31T19:29:00.417",
  "references": [
    {
      "url": "https://github.com/facebook/hhvm/commit/4cb57dd753a339654ca464c139db9871fe961d56",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "cve-assign@fb.com"
    },
    {
      "url": "https://hhvm.com/blog/2018/05/04/hhvm-3.25.3.html",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "cve-assign@fb.com"
    },
    {
      "url": "https://github.com/facebook/hhvm/commit/4cb57dd753a339654ca464c139db9871fe961d56",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://hhvm.com/blog/2018/05/04/hhvm-3.25.3.html",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "cve-assign@fb.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        }
      ]
    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-20"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "A Malformed h2 frame can cause 'std::out_of_range' exception when parsing priority meta data. This behavior can lead to denial-of-service. This affects all supported versions of HHVM (3.25.2, 3.24.6, and 3.21.10 and below) when using the proxygen server to handle HTTP2 requests."
    },
    {
      "lang": "es",
      "value": "Un frame h2 malformado puede provocar una excepción 'std::out_of_range' durante el análisis de metadatos prioritarios. Este comportamiento puede provocar una denegación de servicio (DoS). Esto afecta a todas las versiones de HHVM soportadas (en versiones anteriores a las 3.25.2, 3.24.6 y 3.21.10)"
    }
  ],
  "lastModified": "2026-06-17T02:01:41.137",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "2163DCC3-41A2-4272-97EA-860A6A867914",
              "versionEndIncluding": "3.21.10"
            },
            {
              "criteria": "cpe:2.3:a:facebook:hhvm:3.24.6:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "E7E374ED-033B-4C0C-A056-797A23C17CDC"
            },
            {
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              "matchCriteriaId": "3290E2E7-0F98-418B-82E9-C1779E48A30F"
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          "operator": "OR"
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  "sourceIdentifier": "cve-assign@fb.com"
}