Vulnerability in hackney (CVE-2026-47076)
Summary
Vulnerability in hackney (CVE-2026-47076). Confidential information can be exposed externally. Mitigation: upgrade to 4.0.1 or later.
Original description
The description as published by the source.
Summary
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: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-47076 has been found in hackney.
Confidential information can be exposed externally. CVSS score: 6.5/10.
What to do: upgrade hackney to 4.0.1 or later.
If unsure, ask your IT team or search "hackney CVE-2026-47076" on the vendor's site.
CVE-2026-47076 (hackney) — CWE-436 / CVSS v3 6.5
Attack vector: local / no user interaction
Patched: 4.0.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-436) exists in hackney.
Check the vendor advisory for the affected versions of hackney.
Severity: Medium (CVSS 6.5/10). Confidential information can be exposed externally.
Update to 4.0.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'hackney' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'hackney' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
hackneyを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade hackney to 4.0.1ステージング環境で 4.0.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- package hex.pm
- package github.com
- patch github.com
- web cna.erlef.org
- web osv.dev
- web github.com