How severe is GHSA-px9f-whj3-246m?

No CVSS score has been assigned to GHSA-px9f-whj3-246m yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-px9f-whj3-246m?

GHSA-px9f-whj3-246m affects the following packages: req (Hex). Ecosystems affected: Hex.

How do I fix GHSA-px9f-whj3-246m?

Update req to 0.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-px9f-whj3-246m is resolved across your whole dependency graph.

How do I detect GHSA-px9f-whj3-246m in my Hex dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for req. 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.

How do I mitigate GHSA-px9f-whj3-246m if there is no patch (or I can't update yet)?

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 does O3 Security protect against GHSA-px9f-whj3-246m?

O3 pinpoints whether GHSA-px9f-whj3-246m is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-px9f-whj3-246m actively exploited in the wild?

No public exploit code has been indexed for GHSA-px9f-whj3-246m yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is GHSA-px9f-whj3-246m?

GHSA-px9f-whj3-246m is classified as CWE-93 (CWE-93). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-px9f-whj3-246m published, and has it been updated?

GHSA-px9f-whj3-246m was published on July 29, 2026 and was last updated on July 29, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💧 Hex

GHSA-px9f-whj3-246m

GHSA-px9f-whj3-246m is a CWE-93 vulnerability in req. O3 Security confirms whether GHSA-px9f-whj3-246m is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Req vulnerable to multipart form-data header injection via unescaped name/filename/content_type

Also known asCVE-2026-49756EEF-CVE-2026-49756

Published

Jul 29, 2026

Updated

Jul 29, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

💧req

Real-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

Req's multipart form encoder interpolates the per-part name, filename, and content_type directly into the part headers without escaping. An attacker who can influence any of those values can inject CRLF-separated header lines, smuggle additional form fields, or prepend a whole extra part into the request the victim service sends downstream.

Details

Req.Utils.encode_form_part/2 in lib/req/utils.ex builds the per-part header iodata by concatenating the three caller-supplied strings verbatim into content-disposition: form-data; name="<name>"; filename="<filename>" and content-type: <content_type>. There is no CRLF stripping, no quote escaping, and no validation. A value containing "\r\n closes the surrounding quoted value and starts a new header line; an additional \r\n--<boundary> terminates the current part and lets the attacker prepend a smuggled part.

The flaw is reachable through every supported way of supplying a part. It is especially easy to hit when value is a %File.Stream{}, because filename then defaults to Path.basename(stream.path) and POSIX filenames may legitimately contain \r and \n. RFC 7578 / WHATWG form-data requires percent-encoding ", CR, and LF in these fields; the fix adopts that behavior.

PoC

Construct a malicious filename such as harmless.txt"\r\nX-Smuggled: marker\r\nContent-Disposition: form-data; name="pwned.
Call Req.post!(url, form_multipart: [upload: {"benign body", filename: <malicious>, content_type: "text/plain"}]).
The emitted multipart body contains a real X-Smuggled: header line and an extra Content-Disposition for name="pwned", alongside Req's legitimate headers.

Impact

HTTP request smuggling / multipart parameter smuggling in the HTTP client. Any application using Req to send form_multipart requests where any of name, filename, or content_type can be influenced by an untrusted source is affected, most commonly upload proxies and re-uploaders that derive filename from Path.basename/1 on a user-controlled path.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💧Hex	`req`	≥ 0.5.3&&< 0.6.0	0.6.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for req. 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 req to 0.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-px9f-whj3-246m 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-px9f-whj3-246m 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-px9f-whj3-246m. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary Req's multipart form encoder interpolates the per-part `name`, `filename`, and `content_type` directly into the part headers without escaping. An attacker who can influence any of those values can inject CRLF-separated header lines, smuggle additional form fields, or prepend a whole extra part into the request the victim service sends downstream. ### Details `Req.Utils.encode_form_part/2` in `lib/req/utils.ex` builds the per-part header iodata by concatenating the three caller-supplied strings verbatim into `content-disposition: form-data; name="<name>"; filename="<filename>"` a

O3 Security · Impact-Aware SCA

Is GHSA-px9f-whj3-246m in your dependencies?

O3 detects GHSA-px9f-whj3-246m across Hex dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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