# CVE-2026-112880: hackney HTTP request/response splitting in proxy authentication

Source: https://junglewise.ai/threats/cve-2026-112880-improper-neutralization-of-crlf-sequences-in-http-headers-http  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-26. Updated: 2026-10-26  
License: CC BY 4.0 with a link back

CVE-2026-112880 · Severity: info · Published 2026-10-26

hackney is an HTTP client library used in Erlang/Elixir applications. An attacker who controls the headers in a 407 proxy authentication response can inject carriage return and line feed characters into the Proxy-Authorization header, allowing them to inject additional HTTP headers or split the request. This could enable attackers to bypass authentication checks or manipulate requests sent through HTTP proxies.

Technologies: [Benoitc Hackney](https://junglewise.ai/threats/technologies/benoitc-hackney). Vendors: [Benoitc](https://junglewise.ai/threats/vendors/benoitc).

## Quick answers

**Is CVE-2026-112880 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-112880 being exploited in the wild.

**How severe is CVE-2026-112880?** Informational severity, published 26 October 2026.

**Which products and versions are affected?** Benoitc Hackney 2.0.0 before 4.9.0.

**Is there a fix for CVE-2026-112880?** Yes: fixed in hackney 4.9.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-112880 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-112880?** Check whether you run Benoitc 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.

## How to fix

- Fixed in hackney 4.9.0

## Technical details

The vulnerability is an improper neutralization of CRLF sequences (HTTP request/response splitting) in the hackney_http_connect module's handle_proxy_auth/11 function. When a 407 response is received from an HTTP CONNECT proxy, the library invokes a caller-supplied proxy_auth_fun callback with the response headers; if the callback returns a binary containing CR, LF, or NUL bytes, these are written directly into the Proxy-Authorization header without validation, allowing header injection. The attacker must control data that influences the callback's return value, such as proxy challenge headers.

## Affected products

- benoitc hackney 2.0.0 before 4.9.0

## Timeline

- 2026-10-26: disclosed

## References

- [https://repo.hex.pm/](https://repo.hex.pm/)
- [https://github.com/](https://github.com/)

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