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.
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-6cp8-v795-jr2j | Hackney has an infinite loop on non-token byte at start of an Alt-Svc entry |
Wed, 27 May 2026 14:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
Tue, 26 May 2026 21:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Mon, 25 May 2026 14:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Infinite loop in Alt-Svc header parser in hackney | |
| First Time appeared |
Benoitc
Benoitc hackney |
|
| Weaknesses | CWE-835 | |
| CPEs | cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Benoitc
Benoitc hackney |
|
| References |
| |
| Metrics |
cvssV4_0
|
Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-05-27T15:40:41.946Z
Reserved: 2026-05-18T17:28:08.321Z
Link: CVE-2026-47066
Updated: 2026-05-26T15:50:42.912Z
Status : Analyzed
Published: 2026-05-25T15:16:21.597
Modified: 2026-06-17T10:54:17.127
Link: CVE-2026-47066
No data.
OpenCVE Enrichment
Updated: 2026-05-25T22:00:12Z
Github GHSA