PT-2026-43072 · Benoitc · Hackney

Benoit Chesneau + 2 · Published 2026-05-25 · Updated 2026-05-25 · CVE-2026-47076

Mitre

CVSS v4.0

6.9

Medium

Base vector

AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

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.

Fix

SSRF

Weakness Enumeration

CWE-918

CWE-436

Related Identifiers

CVE-2026-47076

Affected Products

Hackney

References · 4

• https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068f · Patch
• https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjq · Vendor Advisory
• https://cna.erlef.org/cves/CVE-2026-47076.html · Note
• https://osv.dev/vulnerability/EEF-CVE-2026-47076 · Note