Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Benoitc | Hackney | >= 0.13.0, < 4.0.1 |
Related Weaknesses (CWE)
References
- https://cna.erlef.org/cves/CVE-2026-47076.htmlPatchThird Party Advisory
- https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b4206Patch
- https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjqExploitPatchVendor Advisory
- https://osv.dev/vulnerability/EEF-CVE-2026-47076PatchThird Party Advisory
- https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjqExploitPatchVendor Advisory
FAQ
What is CVE-2026-47076?
CVE-2026-47076 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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{} ...
How severe is CVE-2026-47076?
CVE-2026-47076 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-47076?
Check the references section above for vendor advisories and patch information. Affected products include: Benoitc Hackney.