CVE-2026-22779
📋 TL;DR
CVE-2026-22779 is a CRLF injection vulnerability in BlackSheep's HTTP Client implementation that allows attackers to modify HTTP requests by injecting malicious headers when developers pass unsanitized user input directly into headers. This affects applications using BlackSheep versions prior to 2.4.6 where user-controlled data is passed to HTTP client headers. The server component is not affected.
💻 Affected Systems
- BlackSheep
📦 What is this software?
Blacksheep by Neoteroi
⚠️ Risk & Real-World Impact
Worst Case
Attackers could inject arbitrary HTTP headers, create new HTTP requests, potentially leading to request smuggling, SSRF attacks, or manipulation of downstream services.
Likely Case
Header injection allowing modification of HTTP requests to backend services, potentially bypassing security controls or manipulating API calls.
If Mitigated
Limited impact if proper input validation and sanitization are implemented before passing data to HTTP client headers.
🎯 Exploit Status
Exploitation requires developer misuse by passing unsanitized user input to HTTP client headers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.4.6
Vendor Advisory: https://github.com/Neoteroi/BlackSheep/security/advisories/GHSA-6pw3-h7xf-x4gp
Restart Required: Yes
Instructions:
1. Update BlackSheep to version 2.4.6 or later using pip: pip install --upgrade blacksheep>=2.4.6
2. Restart all affected applications
3. Verify no custom code passes unsanitized user input to HTTP client headers
🔧 Temporary Workarounds
Input Validation and Sanitization
allImplement strict input validation and sanitization for any user-controlled data before passing to HTTP client headers
Header Whitelisting
allImplement a whitelist of allowed headers and reject any headers not on the list
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all user input passed to HTTP client headers
- Use a proxy or middleware to validate and sanitize HTTP headers before they reach the vulnerable component
🔍 How to Verify
Check if Vulnerable:
Check if BlackSheep version is below 2.4.6 and if any code passes user input directly to HTTP client headersCheck Version:
python -c "import blacksheep; print(blacksheep.__version__)"Verify Fix Applied:
Verify BlackSheep version is 2.4.6 or higher and test that user input cannot inject CRLF sequences into headers📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP headers in outbound requests
- CRLF sequences in HTTP headers
- Unexpected header injection attempts
Network Indicators:
- Malformed HTTP requests with injected headers
- Unexpected header values in outbound traffic
SIEM Query:
Search for outbound HTTP requests with suspicious header patterns or CRLF injection attempts