What’s Vulnerable › Vulnerabilities

CVE-2026-22779: BlackSheep ClientSession is vulnerable to CRLF injection

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-01-14 · updated 2026-06-17
• Weakness: CWE-113

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.

Affected products

• Neoteroi BlackSheep: before 2.4.6 — fixed in 2.4.6

How to fix

Upgrade to a fixed version: Neoteroi BlackSheep 2.4.6. Check the vendor advisory for mitigations.

References

• https://github.com/Neoteroi/BlackSheep/commit/bd4ecb9542b5d52442276b5a6907931b90f38d12
• https://github.com/Neoteroi/BlackSheep/releases/tag/v2.4.6
• https://github.com/Neoteroi/BlackSheep/security/advisories/GHSA-6pw3-h7xf-x4gp

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