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CVE-2026-47076— SSRF allowlist bypass via percent-encoded host in hackney

Quick assessment

Affected
benoitc hackney
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Hackney是Hackney公司的一个程序库。 hackney 0.13.0至4.0.1之前版本存在安全漏洞，该漏洞源于URL规范化函数对主机组件进行URL解码，可能导致服务端请求伪造。

AI Predicted 8.5 Difficulty: Easy EPSS 0.16% · P5

Affected Version Matrix 2

VendorProduct Version RangeStatus
benoitc hackney 0.13.0< 4.0.1 affected
4d725507588942fd00efca15b86da3273656510a< 452620a92ec1da2e6b4862a049a2a4f04b42068f affected
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I. Basic Information for CVE-2026-47076

Vulnerability Information
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Vulnerability Title
SSRF allowlist bypass via percent-encoded host in hackney
Source: CVE Program / CVE List V5
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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
解释冲突
Source: CVE Program / CVE List V5
Vulnerability Title
Hackney 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Hackney是Hackney公司的一个程序库。 hackney 0.13.0至4.0.1之前版本存在安全漏洞，该漏洞源于URL规范化函数对主机组件进行URL解码，可能导致服务端请求伪造。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
benoitc hackney 0.13.0 ~ 4.0.1 cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*
benoitc hackney 4d725507588942fd00efca15b86da3273656510a ~ 452620a92ec1da2e6b4862a049a2a4f04b42068f cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-47076

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III. Intelligence Information for CVE-2026-47076

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Patches & Fixes for CVE-2026-47076 (1)

Vendor Advisories for CVE-2026-47076 (2)

Other References for CVE-2026-47076 (1)

Same Patch Batch · benoitc · 2026-05-25 · 10 CVEs total

CVE-2026-47075 6.8 MEDIUM CR/LF injection in query parameter in hackney
CVE-2026-47070 HTTP/3 redirect handler leaks Authorization and Cookie headers to cross-origin redirect ta
CVE-2026-47069 CRLF injection in cookie domain/path options in hackney
CVE-2026-47073 Unbounded memory consumption in WebSocket client in hackney
CVE-2026-47072 CRLF injection in WebSocket upgrade request in hackney
CVE-2026-47077 Unbounded body accumulation in HTTP/3 response loop in hackney
CVE-2026-47067 Atom table exhaustion via unrecognized URL schemes in hackney
CVE-2026-47071 SOCKS5 TLS upgrade ignores caller timeout in hackney
CVE-2026-47066 Infinite loop in Alt-Svc header parser in hackney

IV. Related Vulnerabilities

Same product: hackney
Same vendor: benoitc
Same weakness: CWE-436

V. Comments for CVE-2026-47076

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