CVE-2026-47076
SSRF allowlist bypass via percent-encoded host in hackney
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.
INFO
Published Date :
May 25, 2026, 3:16 p.m.
Last Modified :
May 27, 2026, 1:51 p.m.
Remotely Exploit :
No
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update hackney to a patched version.
- Review URL handling and parsing logic.
- Implement strict host validation.
- Validate all URLs before processing.
Public PoC/Exploit Available at Github
CVE-2026-47076 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-47076.
| URL | Resource |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-47076.html | Third Party Advisory Patch |
| https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068f | Patch |
| https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjq | Exploit Vendor Advisory Patch |
| https://osv.dev/vulnerability/EEF-CVE-2026-47076 | Third Party Advisory Patch |
| https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjq | Exploit Vendor Advisory Patch |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-47076 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-47076
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Web scraper to extract data from web pages and XML sitemaps
Elixir
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-47076 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-47076 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 27, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N Added CPE Configuration OR *cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:* versions from (including) 0.13.0 up to (excluding) 4.0.1 Added Reference Type EEF: https://cna.erlef.org/cves/CVE-2026-47076.html Types: Patch, Third Party Advisory Added Reference Type EEF: https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068f Types: Patch Added Reference Type CISA-ADP: https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjq Types: Exploit, Patch, Vendor Advisory Added Reference Type EEF: https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjq Types: Exploit, Patch, Vendor Advisory Added Reference Type EEF: https://osv.dev/vulnerability/EEF-CVE-2026-47076 Types: Patch, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 26, 2026
Action Type Old Value New Value Added Reference https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjq -
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
May. 25, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 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 Added CWE CWE-918 Added CWE CWE-436 Added Reference https://cna.erlef.org/cves/CVE-2026-47076.html Added Reference https://github.com/benoitc/hackney/commit/452620a92ec1da2e6b4862a049a2a4f04b42068f Added Reference https://github.com/benoitc/hackney/security/advisories/GHSA-pj7v-xfvx-wmjq Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-47076