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How the CVE Works
The vulnerability stems from an improperly implemented connection limiter in letmein services (letmeind and letmeinfwd). The `num-connections` command-line option fails to restrict simultaneous incoming connections (TCP, UDP, Unix socket), allowing unlimited connections. letmeind, the public-facing daemon, and letmeinfwd, the internal firewall daemon, are both affected. Attackers can exploit this flaw to launch resource-exhaustion Denial-of-Service (DoS) attacks, overwhelming the service and causing unresponsiveness.
DailyCVE Form
Platform: letmein
Version: <= 10.2.0
Vulnerability: DoS
Severity: Critical
Date: 2023-XX-XX
Prediction: Patch by 2023-11-30
What Undercode Say
Check active connections netstat -tnp | grep letmeind Mitigation (firewall rule) iptables -A INPUT -p tcp --dport 5800 -m connlimit --connlimit-above 100 -j DROP Systemd resource limit systemctl set-property letmeind.service TasksMax=500
Exploit
- Flood target with excessive connections via `letmeind` (TCP/UDP 5800).
- Overwhelm `letmeinfwd` via Unix socket connections.
- Bypasses `num-connections` restriction.
Protection from this CVE
- Upgrade to v10.2.1.
- Enforce firewall connection limits.
- Apply systemd resource constraints.
Impact
- Service unresponsiveness.
- Resource exhaustion (CPU/memory).
- Potential system instability.
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
