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FKIE_CVE-2026-47066

Vulnerability from fkie_nvd - Published: 2026-05-25 15:16 - Updated: 2026-07-24 10:10
Severity
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation. The Alt-Svc response header parser in src/hackney_altsvc.erl does not guarantee forward progress. When parse_token/2 receives a non-token, non-whitespace, non-comma byte (e.g. !, @, =, ;), it returns the input unchanged. skip_comma/1 also returns the buffer unchanged when the first byte is not a comma. parse_entries/2 then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns. The entry point parse_and_cache/3 is called synchronously in the connection process on every HTTP response. A single-byte Alt-Svc: ! response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to. This issue affects hackney: from 2.0.0-beta.1 before 4.0.1.
References
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://cna.erlef.org/cves/CVE-2026-47066.htmlPatch, Third Party Advisory
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/benoitc/hackney/commit/e548aba1f97ffa3f4750da7b772998fb78c01894Patch
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2jExploit, Patch, Vendor Advisory
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://osv.dev/vulnerability/EEF-CVE-2026-47066Patch, Third Party Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2jExploit, Patch, Vendor Advisory
Impacted products
Vendor Product Version
benoitc hackney *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "hackney_altsvc"
          ],
          "packageName": "hackney",
          "packageURL": "pkg:hex/hackney",
          "product": "hackney",
          "programFiles": [
            "src/hackney_altsvc.erl"
          ],
          "programRoutines": [
            {
              "name": "hackney_altsvc:parse_entries/2"
            },
            {
              "name": "hackney_altsvc:parse_entry/1"
            },
            {
              "name": "hackney_altsvc:parse_protocol/1"
            },
            {
              "name": "hackney_altsvc:parse_token/2"
            },
            {
              "name": "hackney_altsvc:skip_comma/1"
            }
          ],
          "repo": "https://github.com/benoitc/hackney",
          "vendor": "benoitc",
          "versions": [
            {
              "lessThan": "4.0.1",
              "status": "affected",
              "version": "2.0.0-beta.1",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "hackney_altsvc"
          ],
          "packageName": "benoitc/hackney",
          "packageURL": "pkg:github/benoitc/hackney",
          "product": "hackney",
          "programFiles": [
            "src/hackney_altsvc.erl"
          ],
          "programRoutines": [
            {
              "name": "hackney_altsvc:parse_entries/2"
            },
            {
              "name": "hackney_altsvc:parse_entry/1"
            },
            {
              "name": "hackney_altsvc:parse_protocol/1"
            },
            {
              "name": "hackney_altsvc:parse_token/2"
            },
            {
              "name": "hackney_altsvc:skip_comma/1"
            }
          ],
          "repo": "https://github.com/benoitc/hackney",
          "vendor": "benoitc",
          "versions": [
            {
              "lessThan": "e548aba1f97ffa3f4750da7b772998fb78c01894",
              "status": "affected",
              "version": "408e5fe20302226ea8c74dde2bcbd452d712b5b2",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "B119C170-E9CA-4AEE-BE04-F074E70CBF82",
              "versionEndExcluding": "4.0.1",
              "versionStartIncluding": "2.0.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Loop with Unreachable Exit Condition (\u0027Infinite Loop\u0027) vulnerability in benoitc hackney allows Excessive Allocation. The Alt-Svc response header parser in src/hackney_altsvc.erl does not guarantee forward progress. When parse_token/2 receives a non-token, non-whitespace, non-comma byte (e.g. !, @, =, ;), it returns the input unchanged. skip_comma/1 also returns the buffer unchanged when the first byte is not a comma. parse_entries/2 then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns.\n\nThe entry point parse_and_cache/3 is called synchronously in the connection process on every HTTP response. A single-byte Alt-Svc: ! response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to.\n\nThis issue affects hackney: from 2.0.0-beta.1 before 4.0.1."
    },
    {
      "lang": "es",
      "value": "Vulnerabilidad de bucle con condici\u00f3n de salida inalcanzable (\u0027Bucle Infinito\u0027) en benoitc hackney permite asignaci\u00f3n excesiva. El analizador de encabezados de respuesta Alt-Svc en src/hackney_altsvc.erl no garantiza el progreso hacia adelante. Cuando parse_token/2 recibe un byte que no es un token, no es un espacio en blanco, no es una coma (p. ej. \u0027!\u0027, \u0027@\u0027, \u0027=\u0027, \u0027;\u0027), devuelve la entrada sin cambios. skip_comma/1 tambi\u00e9n devuelve el b\u00fafer sin cambios cuando el primer byte no es una coma. parse_entries/2 luego recurre con datos id\u00e9nticos, creando un bucle recursivo de cola infinito y ajustado que fija un planificador al 100% de CPU. El proceso de llamada nunca regresa.\n\nEl punto de entrada parse_and_cache/3 se llama sincr\u00f3nicamente en el proceso de conexi\u00f3n en cada respuesta HTTP. Un encabezado de respuesta Alt-Svc: \u0027!\u0027 de un solo byte es suficiente para activar el bloqueo; el encabezado est\u00e1 totalmente controlado por cualquier origen HTTP al que se conecta el cliente.\n\nEste problema afecta a hackney: desde 2.0.0-beta.1 antes de 4.0.1."
    }
  ],
  "id": "CVE-2026-47066",
  "lastModified": "2026-07-24T10:10:00.197",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.7,
          "baseSeverity": "HIGH",
          "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": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/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": "HIGH",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-47066",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-26T15:50:47.725364Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-05-25T15:16:21.597",
  "references": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://cna.erlef.org/cves/CVE-2026-47066.html"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/benoitc/hackney/commit/e548aba1f97ffa3f4750da7b772998fb78c01894"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "tags": [
        "Exploit",
        "Patch",
        "Vendor Advisory"
      ],
      "url": "https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-47066"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Patch",
        "Vendor Advisory"
      ],
      "url": "https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j"
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-835"
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary"
    }
  ]
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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