CVE-2024-50608
📋 TL;DR
CVE-2024-50608 is a NULL pointer dereference vulnerability in Fluent Bit's Prometheus Remote Write input plugin that allows remote denial of service attacks. When an attacker sends a packet with Content-Length: 0 to the listening endpoint, it crashes the Fluent Bit server due to improper handling. This affects organizations using Fluent Bit 3.1.9 with the Prometheus Remote Write plugin exposed.
💻 Affected Systems
- Fluent Bit
📦 What is this software?
Fluent Bit by Treasuredata
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption of Fluent Bit, causing log processing pipeline failure and potential data loss if logs aren't buffered elsewhere.
Likely Case
Intermittent Fluent Bit crashes requiring manual restart, disrupting log collection and monitoring capabilities.
If Mitigated
Minimal impact if plugin isn't exposed or proper network controls prevent access to the vulnerable endpoint.
🎯 Exploit Status
Simple HTTP request with Content-Length: 0 header triggers the crash, no authentication required if endpoint is accessible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Fluent Bit releases after 3.1.9 for fix
Vendor Advisory: https://fluentbit.io/announcements/
Restart Required: Yes
Instructions:
1. Check current Fluent Bit version. 2. Update to patched version from official releases. 3. Restart Fluent Bit service.
🔧 Temporary Workarounds
Disable Prometheus Remote Write Plugin
allRemove or comment out Prometheus Remote Write input configuration if not needed
# Edit fluent-bit.conf and remove [INPUT] section with Type prometheus_remote_write
Network Access Control
linuxRestrict network access to Fluent Bit's Prometheus Remote Write endpoint using firewall rules
# Example iptables: iptables -A INPUT -p tcp --dport [PORT] -s [ALLOWED_IPS] -j ACCEPT
# Then: iptables -A INPUT -p tcp --dport [PORT] -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to limit access to Fluent Bit endpoints
- Deploy Web Application Firewall (WAF) or reverse proxy to filter malicious requests before reaching Fluent Bit
🔍 How to Verify
Check if Vulnerable:
Check if Fluent Bit version is 3.1.9 and Prometheus Remote Write plugin is configured in fluent-bit.confCheck Version:
fluent-bit --versionVerify Fix Applied:
After patching, test by sending HTTP request with Content-Length: 0 to the endpoint - service should not crash📡 Detection & Monitoring
Log Indicators:
- Fluent Bit crash logs
- Segmentation fault errors in system logs
- Unexpected Fluent Bit process termination
Network Indicators:
- HTTP requests with Content-Length: 0 header to Fluent Bit ports
- Multiple connection attempts to Prometheus Remote Write endpoint
SIEM Query:
source="fluent-bit" AND ("segmentation fault" OR "crash" OR "SIGSEGV")