GHSA-cq46-m9x9-j8w2 Scapy Session Loading Vulnerable to Arbitrary Code Execution via Untrusted Pickle Deserialization

• PyPI scapy: <= 2.6.1 (no fix yet)

Summary An unsafe deserialization vulnerability in Scapy ``` Internally, this triggers: ```python 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 ```python try: s = pickle.load(gzip.open(fname, "rb")) except IOError: try: s = pickle.load(open(fname, "rb")) ``` Impact 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. • Vulnerability type: Insecure deserialization (Python `pickle`) • CWE: CWE-502: Deserialization of Untrusted Data • CVSS v4.0 Vector: `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` • CVSS Score: 5.4 (Medium) • Impact: Arbitrary Code Execution • Attack vector: Local or supply chain (malicious `.pkl.gz`) • Affected users: Any user who loads session files (even interactively) • Affected version: Scapy v2.6.1 --- Mitigations • Do not use 'sessions' (the -s option when launching Scapy). • Use the Scapy 2.7.0+ where the session mechanism has been removed.