GHSA-j9wq-vxxc-94wf
Fix: benoitc/hackney@ca73dd0GHSA-j9wq-vxxc-94wf is a CWE-93 vulnerability in hackney. O3 Security confirms whether GHSA-j9wq-vxxc-94wf is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Hackney has CR/LF injection in query parameter
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-j9wq-vxxc-94wf.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
hackneyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.
Description
Summary
hackney_url:make_url/3 passes the URL query component directly into the HTTP/1.1 request target without percent-encoding \r or \n. RFC 3986 §3.4 requires characters outside the query grammar to be percent-encoded, but no validation or escaping occurs. An attacker who controls any portion of the URL passed to hackney can inject raw CRLF sequences into the request line, enabling HTTP header injection or full request splitting.
Details
hackney_url:make_url/3 in src/hackney_url.erl builds the request target by concatenating the path and query binaries. The query string is used as-is — no character-class check, no percent-encoding of \r or \n. When hackney serializes the request, the query value lands verbatim in the GET <path>?<query> HTTP/1.1\r\n request line. A query value containing \r\n terminates the request line early; subsequent bytes are parsed by the server (or any intermediary proxy) as additional header lines or a second request.
A concrete example: a URL with query ?q=x HTTP/1.1\r\nX-Injected: yes\r\nX: produces the following on the wire:
GET /?q=x HTTP/1.1
X-Injected: yes
X: HTTP/1.1
Host: ...
The server sees X-Injected: yes as a legitimate request header that the client never intended to send.
PoC
- Listen on a raw TCP port:
nc -lvnp 8080. - Issue:
:hackney.get("http://127.0.0.1:8080/?q=x HTTP/1.1\r\nX-Injected: yes\r\nX:"). - Observe the listener receives
X-Injected: yesas a standalone header line in the request.
Impact
HTTP header injection and request splitting against any server hackney connects to. Affects all released versions of hackney before 4.0.1. Exploitation requires an attacker-controlled URL (or URL component) to reach hackney without prior sanitization. Consequences include injecting arbitrary headers (Authorization, Host, X-Forwarded-For) and splitting requests through proxies. CVSS v4.0: 6.8 (MEDIUM).
Resources
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💧Hex | hackney | all versions | 4.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hackney. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update hackney to 4.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-j9wq-vxxc-94wf is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-j9wq-vxxc-94wf is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-j9wq-vxxc-94wf. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-j9wq-vxxc-94wf in your dependencies?
O3 detects GHSA-j9wq-vxxc-94wf across Hex dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.