Listen to this Post
The vulnerability exploits the Nnssf_NSSAIAvailability API in Free5GC by sending a maliciously crafted POST request. This API, part of the Network Slice Selection Function, fails to properly validate input size and structure. An attacker can send a request with an excessively large payload, malformed JSON, or deeply nested objects. The inadequate error handling causes the service to enter an infinite loop or crash due to memory corruption. Specifically, the parsing logic does not enforce limits on the request body, leading to resource exhaustion. The service may become unresponsive, terminating critical 5G core network functions. This attack is remote and requires no authentication, making it easily exploitable. The crafted request triggers a bug in the API’s processing routine, which consumes all available CPU or memory. This results in a denial of service, preventing legitimate users from accessing network slice availability information. The vulnerability is confirmed in versions v4.0.0 and v4.0.1, where the API endpoint is exposed by default. Attackers can reliably crash the service with minimal effort, disrupting mobile network operations. Mitigation involves patching the software or implementing external input validation controls.
Platform: Free5GC
Version: v4.0.0, v4.0.1
Vulnerability: Denial of Service
Severity: Critical
Date: 2025-11-24
Prediction: Expected patch by 2025-12-08
What Undercode Say:
Analytics:
Check Free5GC NSSF service status
ps aux | grep nssf
Monitor API access logs
tail -f /var/log/free5gc/nssf.log
Send test POST request
curl -X POST http://localhost:29510/api/nnssf-nssaiavailability -H “Content-Type: application/json” -d ‘{“key”:”value”}’
Python script to send payload
import requests
requests.post(“http://target/api/nnssf-nssaiavailability”, json={“data”:”A”10000})
How Exploit:
Send crafted POST request to Nnssf_NSSAIAvailability API endpoint with malformed data to crash service.
Protection from this CVE:
Apply vendor patches, restrict network access to API, implement input validation, use WAF.
Impact:
Service outage, disrupted 5G network slice management, potential mobile service degradation.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
