CVE-2026-22779 BlackSheep ClientSession is vulnerable to CRLF injection
Attackers can inject CRLF sequences into HTTP headers via unsanitized input, potentially modifying requests or creating new ones in BlackSheep client sessions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-22779?
CVE-2026-22779 is a medium-severity vulnerability in Neoteroi BlackSheep, published on 14 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
BlackSheep is an asynchronous web framework to build event based web applications with Python. Prior to 2.4.6, 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. This vulnerability is fixed in 2.4.6.
Weakness: CWE-113
Which versions are affected by CVE-2026-22779?
3 open source packages ship an affected version, including blacksheep. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
blacksheep PyPI | All versions | 2.4.6 |
blacksheep PyPI | All versions | 2.4.6 |
blacksheep PyPI | All versions | 2.4.6 |
Products include Neoteroi Blacksheep.
How do I fix CVE-2026-22779?
Upgrade blacksheep to 2.4.6 or later.
Is CVE-2026-22779 being exploited?
There is no known exploitation of CVE-2026-22779 in the wild and no public exploit code.
Sources
Also known as GHSA-6pw3-h7xf-x4gp, PYSEC-2026-1222.