CVE-2026-47076
SSRF allowlist bypass via percent-encoded host in hackney
At a glance
- Source
- NVD
- EPSS
- EPSS 0.23 % · percentile 14 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- EEF
- NVD status
- Analyzed
Description
Interpretation Conflict vulnerability in benoitc hackney allows Server Side Request Forgery. hackney_url:normalize/2 URL-decodes the host component after the URL has been parsed into a #hackney_url{} record. OTP's uri_string:parse/1 and inet:parse_address/1 do not decode percent-escapes in the host, so a URL such as http://%31%32%37%2E%30%2E%30%2E%31/ is seen by a caller's allowlist validator with host %31%32%37%2E%30%2E%30%2E%31 (not an IP address), which passes the allowlist check. hackney's normalizer then decodes the host to 127.0.0.1 and opens a TCP connection to loopback. Because hackney:request/5 always calls hackney_url:normalize/2 with no opt-out, every request that takes a binary or list URL is affected. The same technique reaches cloud instance metadata services (169.254.169.254), RFC1918 networks, and any admin interface listening on localhost. This issue affects hackney: from 0.13.0 before 4.0.1.
Weaknesses (CWE)
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | MEDIUM 6.9 | CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N | EEF |
| CVSS 4.0 | MEDIUM 6.9 | CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/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 | NVD · 6b3ad84c-e1a6-4bf7-a703-f496b71e49db (Secondary) |
| CVSS 3.1 | MEDIUM 6.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N | NVD · nvd@nist.gov (Primary) |
European references
- ENISA EUVD · EUVD-2026-31689
- GCVE · GCVE-0-2026-47076
Affected configurations (NVD CPE)
cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*≥ 0.13.0 < 4.0.1
Affected products
| Product | Versions |
|---|---|
| benoitc · hackney | affected 0.13.0 < 4.0.1 |
| benoitc · hackney | affected 4d725507588942fd00efca15b86da3273656510a < 452620a92ec1da2e6b4862a049a2a4f04b42068f |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |