CVE-2026-22779CWE-113

BlackSheep ClientSession is vulnerable to CRLF injection

Medium · published January 14, 2026

CVSS v4.0
6.3
EPSS
0%
Percentile
29.4
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
6.3 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
EPSS
0.00368 · 29.4th percentile
Weakness
CWE-113 · Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
Published
2026-01-14T16:49Z
EPSS history
Timeline
  • 14 JAN 16:49Z
    BlackSheep ClientSession is vulnerable to CRLF injection
    cvelistv5