---
id: CVE-2026-22779
aliases:
  - GHSA-6pw3-h7xf-x4gp
  - PYSEC-2026-1222
title: BlackSheep's ClientSession is vulnerable to CRLF injection
summary: BlackSheep's ClientSession is vulnerable to CRLF injection
severity: medium
vendor: blacksheep
product: blacksheep
ecosystem: pip
affected:
  - blacksheep < 2.4.6
patched:
  - blacksheep 2.4.6
published: '2026-01-14'
updated: '2026-07-07'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-6pw3-h7xf-x4gp'
references:
  - url: >-
      https://github.com/Neoteroi/BlackSheep/security/advisories/GHSA-6pw3-h7xf-x4gp
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-22779'
  - url: >-
      https://github.com/Neoteroi/BlackSheep/commit/bd4ecb9542b5d52442276b5a6907931b90f38d12
  - url: 'https://github.com/Neoteroi/BlackSheep'
  - url: 'https://github.com/Neoteroi/BlackSheep/releases/tag/v2.4.6'
tags:
  - osv
  - pip
epss: 0.00359
epssPercentile: 0.26932
ingestedAt: '2026-07-08T18:25:46.507Z'
---

## Overview

### Impact
The HTTP Client implementation in BlackSheep is vulnerable to CRLF injection. Missing headers validation makes it possible for an attacker to modify the HTTP requests (e.g. insert a new header) or even create a new HTTP request.
Exploitation requires developers to pass unsanitized user input directly into headers.
The server part is not affected because BlackSheep delegates to an underlying ASGI server handling of response headers.

**Attack vector:** Applications using user input in HTTP client requests (method, URL, headers).

### Patches
Users who use the HTTP Client in BlackSheep should upgrade to `2.4.6`.

### Workarounds
If users handle headers from untrusted parties, they might reject values for header names and values that contain carriage returns.

### References
https://owasp.org/www-community/vulnerabilities/CRLF_Injection

## Affected packages

- `blacksheep < 2.4.6`

## Remediation

Upgrade to a patched release:

- `blacksheep 2.4.6`