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VulnerabilityPublished Updated

CVE-2026-47066: benoitc hackney · Infinite Loop

Affects benoitc hackneySource CVE Database V5

0

Not known to be exploited · CVSS 8.7 High : upgrade to 4.0.1 soon.

Data as of 26 Oct 2026, 09:16 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.0.1, e548aba1f97ffa3f4750da7b772998fb78c01894
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade hackney to 4.0.1; hackney to e548aba1f97ffa3f4750da7b772998fb78c01894.

Affected software

ProductAffectedFixed in
benoitchackneyAffected
  • >=2.0.0-beta.1 <4.0.1
Fixed in
  • 4.0.1
benoitchackneyAffected
  • ≥ 408e5fe20302226ea8c74dde2bcbd452d712b5b2, < e548aba1f97ffa3f4750da7b772998fb78c01894
Fixed in
  • e548aba1f97ffa3f4750da7b772998fb78c01894
Hexhackneypkg:hex/hackneyOther threatsAffected
  • =2.0.0-beta.1
  • <4.0.1
Fixed in
  • 4.0.1
Hexhackneypkg:hex/hackneyOther threatsAffected
  • >=2.0.0-beta.1 <4.0.1
Fixed in
  • 4.0.1

CPE configurations (1)

  • cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

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

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