{
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    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-47066",
        "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "state": "PUBLISHED",
        "assignerShortName": "EEF",
        "dateReserved": "2026-05-18T17:28:08.321Z",
        "datePublished": "2026-05-25T14:00:39.707Z",
        "dateUpdated": "2026-05-27T15:40:41.946Z"
    },
    "containers": {
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            "affected": [
                {
                    "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"
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                        {
                            "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"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "cpeMatch": [
                                {
                                    "criteria": "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "4.0.1",
                                    "versionStartIncluding": "2.0.0-beta.1",
                                    "vulnerable": true
                                }
                            ],
                            "negate": false,
                            "operator": "AND"
                        }
                    ],
                    "operator": "AND"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Peter Ullrich"
                },
                {
                    "lang": "en",
                    "type": "remediation developer",
                    "value": "Benoit Chesneau"
                },
                {
                    "lang": "en",
                    "type": "analyst",
                    "value": "Jonatan Männchen / EEF"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation.<p>The Alt-Svc response header parser in <tt>src/hackney_altsvc.erl</tt> does not guarantee forward progress. When <tt>parse_token/2</tt> receives a non-token, non-whitespace, non-comma byte (e.g. <tt>!</tt>, <tt>@</tt>, <tt>=</tt>, <tt>;</tt>), it returns the input unchanged. <tt>skip_comma/1</tt> also returns the buffer unchanged when the first byte is not a comma. <tt>parse_entries/2</tt> then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns.</p><p>The entry point <tt>parse_and_cache/3</tt> is called synchronously in the connection process on every HTTP response. A single-byte <tt>Alt-Svc: !</tt> response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to.</p><p>This issue affects hackney: from 2.0.0-beta.1 before 4.0.1.</p>"
                        }
                    ],
                    "value": "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.\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."
                }
            ],
            "impacts": [
                {
                    "capecId": "CAPEC-130",
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "CAPEC-130 Excessive Allocation"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "attackVector": "NETWORK",
                        "baseScore": 8.7,
                        "baseSeverity": "HIGH",
                        "privilegesRequired": "NONE",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "userInteraction": "NONE",
                        "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",
                        "version": "4.0",
                        "vulnAvailabilityImpact": "HIGH",
                        "vulnConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE"
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                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
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            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-835",
                            "description": "CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')",
                            "lang": "en",
                            "type": "CWE"
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            "providerMetadata": {
                "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
                "shortName": "EEF",
                "dateUpdated": "2026-05-27T15:40:41.946Z"
            },
            "references": [
                {
                    "tags": [
                        "vendor-advisory",
                        "related"
                    ],
                    "url": "https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://cna.erlef.org/cves/CVE-2026-47066.html"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://osv.dev/vulnerability/EEF-CVE-2026-47066"
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                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/benoitc/hackney/commit/e548aba1f97ffa3f4750da7b772998fb78c01894"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "title": "Infinite loop in Alt-Svc header parser in hackney",
            "x_generator": {
                "engine": "cvelib 1.8.0"
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        "adp": [
            {
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                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-05-26T15:50:47.725364Z",
                                "id": "CVE-2026-47066",
                                "options": [
                                    {
                                        "Exploitation": "poc"
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                                    {
                                        "Automatable": "yes"
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                                        "Technical Impact": "partial"
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                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
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                "title": "CISA ADP Vulnrichment",
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                    "dateUpdated": "2026-05-26T15:50:51.330Z"
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