CVE-2026-47066

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.7%, top 51% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 7.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
7.5
EG Score
7.5(medium)
EPSS
49.5%
KEV
Not listed

Published

May 25, 2026

Last Modified

May 27, 2026

Advisory Details (4)

Auto-updated Jun 6, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
github Patch Available🟡 PoC Available

Infinite loop on non-token byte at start of an Alt-Svc entry · Advisory · benoitc/hackney · GitHub

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

OSV - Open Source Vulnerabilities

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

commit e548aba1f97f (benoitc/hackney)

Patch available: benoitc/hackney 4.0.1 (contains commit e548aba1f97f)

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

Infinite loop in Alt-Svc header parser in hackney | Erlang Ecosystem Foundation CNA

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

Vendor Advisories for CVE-2026-47066(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Hex(1)
PackageVulnerable rangeFixed inDependents
hackney2.0.0 ... 4.0.0 (13 versions)4.0.1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 33× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-21 15:24 UTCEPSS rescore
  3. 2026-07-20 17:08 UTCEPSS rescore
  4. 2026-07-19 14:31 UTCEPSS rescore
  5. 2026-07-19 02:29 UTCEPSS rescore
  6. 2026-07-18 10:04 UTCEPSS rescore
  7. 2026-07-17 17:59 UTCOSV refresh
  8. 2026-07-16 17:03 UTCEPSS rescore
  9. 2026-07-15 16:57 UTCEPSS rescore
  10. 2026-07-15 02:00 UTCEPSS rescore
  11. 2026-07-13 22:30 UTCEPSS rescore
  12. 2026-07-13 06:13 UTCEPSS rescore
  13. 2026-07-12 05:46 UTCEPSS rescore
  14. 2026-07-11 08:27 UTCEPSS rescore
  15. 2026-07-09 19:10 UTCEPSS rescore
  16. 2026-07-08 15:16 UTCEPSS rescore
  17. 2026-07-07 13:46 UTCEPSS rescore
  18. 2026-07-06 16:27 UTCEPSS rescore
  19. 2026-07-06 02:23 UTCEPSS rescore
  20. 2026-07-05 02:30 UTCEPSS rescore
  21. 2026-07-04 06:31 UTCEPSS rescore
  22. 2026-07-01 15:07 UTCEPSS rescore
  23. 2026-06-30 23:22 UTCEPSS rescore
  24. 2026-06-29 14:06 UTCEPSS rescore
  25. 2026-06-29 14:06 UTCEPSS rescore
Show 54 more
  1. 2026-06-28 14:07 UTCEPSS rescore
  2. 2026-06-28 04:56 UTCEPSS rescore
  3. 2026-06-28 04:56 UTCEPSS rescore
  4. 2026-06-27 03:08 UTCEPSS rescore
  5. 2026-06-25 13:49 UTCEPSS rescore
  6. 2026-06-24 14:05 UTCEPSS rescore
  7. 2026-06-23 21:33 UTCEPSS rescore
  8. 2026-06-23 21:33 UTCEPSS rescore
  9. 2026-06-22 14:25 UTCEPSS rescore
  10. 2026-06-22 14:25 UTCEPSS rescore
  11. 2026-06-21 14:56 UTCEPSS rescore
  12. 2026-06-21 14:56 UTCEPSS rescore
  13. 2026-06-21 01:59 UTCEPSS rescore
  14. 2026-06-21 01:59 UTCEPSS rescore
  15. 2026-06-19 19:26 UTCEPSS rescore
  16. 2026-06-19 19:26 UTCEPSS rescore
  17. 2026-06-18 17:52 UTCEPSS rescore
  18. 2026-06-18 17:52 UTCEPSS rescore
  19. 2026-06-17 17:53 UTCEPSS rescore
  20. 2026-06-16 17:53 UTCEPSS rescore
  21. 2026-06-15 17:49 UTCEPSS rescore
  22. 2026-06-13 23:00 UTCEPSS rescore
  23. 2026-06-12 23:12 UTCEPSS rescore
  24. 2026-06-12 23:12 UTCEPSS rescore
  25. 2026-06-11 14:00 UTCEPSS rescore
  26. 2026-06-10 22:18 UTCEPSS rescore
  27. 2026-06-10 13:22 UTCEPSS rescore
  28. 2026-06-10 13:22 UTCEPSS rescore
  29. 2026-06-08 14:17 UTCEPSS rescore
  30. 2026-06-08 14:17 UTCEPSS rescore
  31. 2026-06-07 15:25 UTCEPSS rescore
  32. 2026-06-07 15:25 UTCEPSS rescore
  33. 2026-06-06 13:47 UTCEPSS rescore
  34. 2026-06-06 13:47 UTCEPSS rescore
  35. 2026-06-05 22:47 UTCEPSS rescore
  36. 2026-06-05 06:10 UTCEPSS rescore
  37. 2026-06-05 06:10 UTCEPSS rescore
  38. 2026-06-04 13:12 UTCEPSS rescore
  39. 2026-06-04 13:12 UTCEPSS rescore
  40. 2026-06-01 13:52 UTCEPSS rescore
  41. 2026-06-01 13:52 UTCEPSS rescore
  42. 2026-06-01 02:21 UTCEG score recompute▼ 1.20
  43. 2026-05-31 22:30 UTCEPSS rescore
  44. 2026-05-31 22:30 UTCEPSS rescore
  45. 2026-05-31 00:16 UTCEPSS rescore
  46. 2026-05-31 00:16 UTCEPSS rescore
  47. 2026-05-29 13:44 UTCEPSS rescore
  48. 2026-05-29 13:44 UTCEPSS rescore
  49. 2026-05-28 13:44 UTCEPSS rescore
  50. 2026-05-28 13:44 UTCEPSS rescore
  51. 2026-05-27 13:40 UTCEPSS rescore
  52. 2026-05-27 13:40 UTCEPSS rescore
  53. 2026-05-26 13:44 UTCEPSS rescore
  54. 2026-05-25 14:27 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-47066?
CVE-2026-47066 is a high vulnerability published on May 25, 2026. Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation. The Alt-Svc response header parser in src/hackneyaltsvc.erl does not guarantee forward progress. When parsetoken/2 receives a non-token, non-whitespace, non-comma byte (e.g. !, @, =,…
When was CVE-2026-47066 disclosed?
CVE-2026-47066 was first published in the National Vulnerability Database on May 25, 2026, with the most recent update on May 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-47066 actively exploited?
CVE-2026-47066 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 49.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-47066?
CVE-2026-47066 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-47066?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-47066, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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