{"containers":{"cna":{"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"},{"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"}],"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"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-835","description":"CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-05-25T14:00:39.707Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"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"},{"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"}}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-47066","datePublished":"2026-05-25T14:00:39.707Z","dateReserved":"2026-05-18T17:28:08.321Z","dateUpdated":"2026-05-25T14:00:39.707Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"}