CVE-2026-47076
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
hackneyHex | >= 0.13.0, < 4.0.1 | 4.0.1 |
Affected products
3Patches
Vulnerability mechanics
References
6- cna.erlef.org/cves/CVE-2026-47076.htmlnvdPatchThird Party AdvisoryWEB
- github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068fnvdPatchWEB
- osv.dev/vulnerability/EEF-CVE-2026-47076nvdPatchThird Party AdvisoryWEB
- github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjqnvdExploitPatchVendor AdvisoryWEB
- github.com/advisories/GHSA-pj7v-xfvx-wmjqghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-47076ghsaADVISORY
News mentions
1- Hackney HTTP Client: Ten CVEs Disclosed in a Single Batch — CRLF Injection, Resource Exhaustion, and MoreVypr Intelligence · May 25, 2026