External risk intelligence

Picklescan Remote Code Execution via Unblocked Ctypes Module.

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2025-71323

A critical vulnerability in picklescan allows remote code execution by enabling attackers to bypass security measures through specially crafted pickle files. This could lead to unauthorized command execution and memory access if the technology is used in a reachable context. Determining the presence and usage of pickle

Remote Code Execution

Halo Surface Signal

Very unlikely · external exposure

1Halo Surface Signal

Picklescan is a security scanning library used by developers to inspect pickle files for malicious code during build, test, or development workflows. It is not an internet-facing service, appliance, or network gateway, and its typical deployment is within local development environments or CI/CD pipelines, making direct exposure to the public internet very unlikely.

Horizon Alert

Summary of the vulnerability and why it matters

This advisory addresses a critical security vulnerability in the picklescan technology. It concerns a flaw that, if exploited, could allow unauthorized remote code execution by bypassing standard security measures. The primary concern at this stage is to determine if this technology is in use within our environment and to what extent.

Unchecked code execution bypasses security controls.
Confirm relevance and exposure within our systems.
Understand and manage potential system compromise risks.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by sending a specially crafted pickle file to a system that processes it using a vulnerable version of picklescan. This malicious file can trick the system into loading shared libraries and executing arbitrary commands, bypassing security measures.

Entry Condition: Attacker sends a malicious pickle file.
Trigger Point: Processing the pickle file with vulnerable software.
Resulting Risk: Remote code execution and memory access.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to execute arbitrary commands on a system when a specially crafted pickle file is processed by an affected version of picklescan. This bypasses sandbox protections and could lead to unauthorized access or control.

System access and execution of commands.
Crafted pickle files are processed.
Remote code execution and unauthorized control.

Operational Fix

Recommended remediation, mitigation, and detection steps

This advisory impacts users of the `picklescan` library. System owners and security teams should first verify the presence and reachability of `picklescan` within their environments, particularly in build pipelines or development tools. Subsequently, they must identify the accountable owner of these `picklescan` deployments to coordinate a risk-based remediation plan.

Identify accountable application or platform owners.
Verify `picklescan` usage and exposure.
Plan remediation based on identified risk.

Supplementary metadata

PCI scan relevance

Yes

CVE-2025-71323 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

This CVE is PCI relevant due to a remote code execution vulnerability in the picklescan tool, which could allow attackers to bypass security controls.

Scan-prioritization guidance only—not a PCI DSS certification or ASV attestation.

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is picklescan and how is it used?

Picklescan is a security library designed to help developers inspect Python pickle files for potentially malicious code. It is commonly integrated into development workflows, automated testing environments, or continuous integration and deployment (CI/CD) pipelines to safely handle serialized data before execution.

What is the vulnerability in CVE-2025-71323?

This vulnerability, classified as CWE-184 (Incomplete List of Disallowed Inputs), occurs because picklescan fails to block the ctypes module. This weakness allows a crafted pickle file to bypass security checks, letting an attacker invoke system calls or access raw memory directly. By loading system libraries like kernel32.dll, an attacker could achieve remote code execution, effectively rendering the library's intended security inspection ineffective.

How is this vulnerability triggered?

The issue is triggered when an affected version of picklescan processes a specially crafted, malicious pickle file. Simply storing or moving these files does not trigger the flaw; the vulnerability requires the library to actively parse or scan the dangerous file. If the file is never processed by the vulnerable component, the execution path remains inactive.

Is my system at risk from CVE-2025-71323?

According to Halo Surface Signal, risk is very unlikely because picklescan is a development utility rather than an internet-facing service or network gateway. It generally operates within private developer environments or internal build pipelines. You are primarily at risk if your internal systems are configured to process untrusted or externally sourced pickle files using an unpatched version of the library.

How should I respond to this advisory?

First, conduct an inventory to identify where picklescan is deployed within your development tools or CI/CD pipelines. Coordinate with the owners of those specific platforms to verify the current version in use. If you are running a version prior to 0.0.33, plan for an update to a secure version to ensure the ctypes module is correctly blocked.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.