# CVE-2026-47070: benoitc hackney sensitive data exposure in HTTP/3 redirect handler

Source: https://junglewise.ai/threats/cve-2026-47070-benoitc-hackney-sensitive-data-exposure-in-http-3-redirect  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-25. Updated: 2026-06-26  
License: CC BY 4.0 with a link back

CVE-2026-47070 · Severity: medium · CVSS 6 · Published 2026-05-25

Hackney, a popular HTTP client library for Erlang, contains a security flaw in its HTTP/3 implementation. When the library is configured to follow redirects, it may inadvertently send sensitive information—such as login credentials, session cookies, and request data—to an untrusted third-party server if that server issues a redirect. This could allow an attacker to steal user sessions or private data by redirecting a legitimate request to a server they control.

Technologies: [Benoit Chesneau Hackney](https://junglewise.ai/threats/technologies/hackney). Vendors: [Benoit Chesneau](https://junglewise.ai/threats/vendors/benoit-chesneau).

## Quick answers

**Is CVE-2026-47070 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-47070 being exploited in the wild.

**How severe is CVE-2026-47070?** Medium severity, with a CVSS score of 6, published 25 May 2026.

**Which products and versions are affected?** Benoit Chesneau Hackney >= 3.1.1, < 4.0.1.

**Is there a fix for CVE-2026-47070?** A patch was published on 2026-06-26: Fix confirmed in version 4.0.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-47070 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-47070?** Check whether you run Benoit Chesneau Hackney at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability exists in the HTTP/3 redirect handler within `src/hackney_h3.erl` of the Hackney library. The `handle_redirect/11` function fails to verify if a redirect target's host matches the original request's origin before forwarding sensitive headers like `Authorization`, `Cookie`, and `Proxy-Authorization`. For 307 and 308 status codes, the original request body is also forwarded to the new destination. This occurs because the H3 client lacks the `maybe_strip_auth_on_redirect/2` logic present in the library's HTTP/1 implementation. Attackers can exploit this by providing a cross-origin `Location` header to capture credentials from clients with `follow_redirect` enabled. The issue is patched in version 4.0.1.

## Affected products

- benoitc hackney >= 3.1.1, < 4.0.1

## Identifiers

- CVE-2026-47070
- GHSA-h73q-4w9q-82h4

## Timeline

- 2026-05-25: disclosed: Initial disclosure and NVD publication
- 2026-06-26: advisory: GitHub Advisory published/reviewed
- 2026-06-26: patched: Fix confirmed in version 4.0.1

## References

- [https://api.github.com/users/PJUllrich](https://api.github.com/users/PJUllrich)
- [https://github.com/PJUllrich](https://github.com/PJUllrich)
- [https://api.github.com/users/PJUllrich/gists%7B/gist_id%7D](https://api.github.com/users/PJUllrich/gists%7B/gist_id%7D)
- [https://api.github.com/users/PJUllrich/repos](https://api.github.com/users/PJUllrich/repos)
- [https://avatars.githubusercontent.com/u/10426523?v=4](https://avatars.githubusercontent.com/u/10426523?v=4)
- [https://api.github.com/users/PJUllrich/events%7B/privacy%7D](https://api.github.com/users/PJUllrich/events%7B/privacy%7D)

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