{"timestamp":"2026-05-26T15:50:47.725364Z","id":"CVE-2026-47066","options":[{"exploitation":"poc"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}

[{"vendor":"benoitc","product":"hackney","defaultStatus":"unaffected","collectionURL":"https://repo.hex.pm","packageName":"hackney","cpes":["cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"],"modules":["hackney_altsvc"],"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","packageURL":"pkg:hex/hackney","versions":[{"version":"2.0.0-beta.1","lessThan":"4.0.1","versionType":"semver","status":"affected"}]},{"vendor":"benoitc","product":"hackney","defaultStatus":"unaffected","collectionURL":"https://github.com","packageName":"benoitc/hackney","cpes":["cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"],"modules":["hackney_altsvc"],"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","packageURL":"pkg:github/benoitc/hackney","versions":[{"version":"408e5fe20302226ea8c74dde2bcbd452d712b5b2","lessThan":"e548aba1f97ffa3f4750da7b772998fb78c01894","versionType":"git","status":"affected"}]}]

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

OR
          *cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:* versions from (including) 2.0.0 up to (excluding) 4.0.1

CISA-ADP: https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j Types: Exploit, Patch, Vendor Advisory

EEF: https://cna.erlef.org/cves/CVE-2026-47066.html Types: Patch, Third Party Advisory

EEF: https://github.com/benoitc/hackney/commit/e548aba1f97ffa3f4750da7b772998fb78c01894 Types: Patch

EEF: https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j Types: Exploit, Patch, Vendor Advisory

EEF: https://osv.dev/vulnerability/EEF-CVE-2026-47066 Types: Patch, Third Party Advisory

https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j

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.

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

CWE-835

https://cna.erlef.org/cves/CVE-2026-47066.html

https://github.com/benoitc/hackney/commit/e548aba1f97ffa3f4750da7b772998fb78c01894

https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j

https://osv.dev/vulnerability/EEF-CVE-2026-47066