GHSA-m7j5-r2p5-c39r: Picklescan Picklescan Vulnerable To Arbitrary File Vulnerability

MODERATE
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CWE-502
Published
Advisory Summary

GHSA-m7j5-r2p5-c39r is a MODERATE picklescan vulnerable to arbitrary file vulnerability (CWE-502: Deserialization of Untrusted Data) affecting Picklescan libraries in the PyPI ecosystem. The issue involves picklescan vulnerable to arbitrary file create using logging.filehandler. Remediation is available by upgrading affected packages to version 1.0.1.

GHSA-m7j5-r2p5-c39r at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-m7j5-r2p5-c39r
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-502: Deserialization of Untrusted Data
Affected Product Picklescan
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix GHSA-m7j5-r2p5-c39r

To remediate this vulnerability, upgrade all affected Picklescan dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

picklescan fixed: 1.0.1 
pip install picklescan>=1.0.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show picklescan

How to Check if You Are Affected

To determine whether your Python environment is affected by GHSA-m7j5-r2p5-c39r, inspect your installed packages using pip:

pip show picklescan

Analyze the terminal output to locate any version of Picklescan in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.0.1), your application is affected.

Note: The pip show picklescan command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-502: Deserialization of Untrusted Data, where the product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. In Picklescan, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary Unsafe pickle deserialization allows unauthenticated attackers to perform Arbitrary File Creation. By chaining the logging.FileHandler class, an attacker can bypass RCE-focused blocklists to create empty files on the server. The vulnerability allows creating zero-byte files in arbitrary locations but does not permit overwriting or modifying existing files. ### Details The application deserializes untrusted pickle data. While RCE keywords may be blocked, the exploit abuses standard library features: logging.FileHandler: The exploit instantiates this class using its default behavior (append mode). Behavior on Existing Files: If the target file already exists, the handler opens it without modifying its content, resulting in no impact to existing data. Behavior on Non-Existent Files: If the target file does not exist, the handler creates a new zero-byte file with the specified name. ### PoC ```python import pickle class WriteFile: def __reduce__(self): from logging import FileHandler return (FileHandler, ('evil.log',)) with open("bypass_write.pkl", "wb") as f: pickle.dump(WriteFile(), f) handler = pickle.loads(pickle.dumps(WriteFile())) ``` <img width="1201" height="140" alt="313e1cfacbe700e27b6875e49808c52a" src="https://github.com/user-attachments/assets/8873bb54-0f98-41aa-8e7c-a38a245ca428" /> ### Impact This primitive can be used for Filesystem Pollution or Logic Disruption. For example, an attacker could create specific "lock files" (e.g., maintenance.lock, .lock) that the application checks for, potentially triggering a Denial of Service (DoS) or preventing the application from starting.

GHSA-m7j5-r2p5-c39r Affected Picklescan Versions

1 component(s)
Fixed Versions:
1.0.1
Product / Package Ecosystem Affected Versions Fixed Version
picklescan
pypi/picklescan
PyPI
< 1.0.1
1.0.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/mmaitre314/picklescan/security/advisories/GHSA-m7j5-r2p5-c39r
Picklescan Source Repository REPOSITORY
https://github.com/mmaitre314/picklescan/pull/60
Security Fix Commit FIX COMMIT
https://github.com/mmaitre314/picklescan/commit/4d9bc9cd34bca8672dad3481cd4556d5ba747156
Picklescan Source Repository REPOSITORY
https://github.com/mmaitre314/picklescan
Picklescan Release RELEASE
https://github.com/mmaitre314/picklescan/releases/tag/v1.0.1
Picklescan Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/picklescan/PYSEC-2026-225.yaml
www.vulncheck.com/advisories/picklesc... WEB
https://www.vulncheck.com/advisories/picklescan-arbitrary-file-creation-via-logging-filehandler-deserialization

Frequently Asked Questions

What is GHSA-m7j5-r2p5-c39r?
GHSA-m7j5-r2p5-c39r is a security vulnerability in Picklescan involving picklescan vulnerable to arbitrary file create using logging.FileHandler under CWE-502: Deserialization of Untrusted Data.
Which Picklescan versions are affected?
Affected versions include releases prior to 1.0.1 across affected packages: picklescan.
What version fixes GHSA-m7j5-r2p5-c39r?
Upgrading to 1.0.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is picklescan affected?
Yes, picklescan is affected in releases prior to 1.0.1. Upgrade your dependency to 1.0.1 or later.
What CWE is associated with GHSA-m7j5-r2p5-c39r?
GHSA-m7j5-r2p5-c39r is classified under CWE-502: Deserialization of Untrusted Data (The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.).
How can I check PyPI dependencies for GHSA-m7j5-r2p5-c39r?
Run the dependency tree command: 'pip show picklescan'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-m7j5-r2p5-c39r",
  "modified" : "2026-07-21T14:45:10Z",
  "published" : "2026-02-02T20:50:30Z",
  "aliases" : [ ],
  "summary" : "picklescan vulnerable to arbitrary file create using logging.FileHandler",
  "details" : "### Summary\nUnsafe pickle deserialization allows unauthenticated attackers to perform Arbitrary File Creation. By chaining the logging.FileHandler class, an attacker can bypass RCE-focused blocklists to create empty files on the server. The vulnerability allows creating zero-byte files in arbitrary locations but does not permit overwriting or modifying existing files.\n\n### Details\nThe application deserializes untrusted pickle data. While RCE keywords may be blocked, the exploit abuses standard library features:\n\nlogging.FileHandler: The exploit instantiates this class using its default behavior (append mode).\n\nBehavior on Existing Files: If the target file already exists, the handler opens it without modifying its content, resulting in no impact to existing data.\n\nBehavior on Non-Existent Files: If the target file does not exist, the handler creates a new zero-byte file with the specified name.\n\n### PoC\n```python\nimport pickle\n\nclass WriteFile:\n    def __reduce__(self):\n        from logging import FileHandler\n        return (FileHandler, ('evil.log',))\n    \nwith open(\"bypass_write.pkl\", \"wb\") as f:\n    pickle.dump(WriteFile(), f)\n\nhandler = pickle.loads(pickle.dumps(WriteFile()))\n```\n<img width=\"1201\" height=\"140\" alt=\"313e1cfacbe700e27b6875e49808c52a\" src=\"https://github.com/user-attachments/assets/8873bb54-0f98-41aa-8e7c-a38a245ca428\" />\n\n\n### Impact\nThis primitive can be used for Filesystem Pollution or Logic Disruption. For example, an attacker could create specific \"lock files\" (e.g., maintenance.lock, .lock) that the application checks for, potentially triggering a Denial of Service (DoS) or preventing the application from starting.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "picklescan"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.0.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/mmaitre314/picklescan/security/advisories/GHSA-m7j5-r2p5-c39r"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mmaitre314/picklescan/pull/60"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mmaitre314/picklescan/commit/4d9bc9cd34bca8672dad3481cd4556d5ba747156"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mmaitre314/picklescan"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mmaitre314/picklescan/releases/tag/v1.0.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/picklescan/PYSEC-2026-225.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/picklescan-arbitrary-file-creation-via-logging-filehandler-deserialization"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-02T20:50:30Z",
    "nvd_published_at" : null
  }
}