Executive Summary

CVE-2026-40044 is a critical deserialization vulnerability in Pachno version 1.0.6, specifically in the FileCache component. It allows unauthenticated attackers to execute arbitrary code by injecting malicious serialized PHP objects into cache files.

These cache files are world-writable and have predictable names within the cache directory. During the framework bootstrap process, these cache files are unserialized before any authentication checks occur, which enables attackers to exploit this flaw to run arbitrary code on the system.

The vulnerability arises from the unsafe deserialization of untrusted data, highlighting the risks associated with handling serialized objects insecurely.

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Impact Analysis

This vulnerability can have severe impacts as it allows unauthenticated remote attackers to execute arbitrary code on the affected system.

By exploiting this flaw, attackers can potentially take full control of the system, leading to data breaches, system compromise, and disruption of services.

Because the cache files are world-writable and the deserialization happens before authentication, attackers do not need any prior access or credentials to exploit this vulnerability.

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Detection Guidance

This vulnerability can be detected by checking for the presence of world-writable cache files with predictable names in the Pachno cache directory, as these files are the target for malicious serialized PHP object injection.

You can use commands to identify such files and their permissions. For example, on a Unix-like system, you might run:

• find /path/to/pachno/cache -type f -perm -o+w -ls
• grep -r 'O:8:"PHPObject"' /path/to/pachno/cache

These commands help locate world-writable cache files and search for suspicious serialized PHP objects that could indicate exploitation attempts.

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Mitigation Strategies

Immediate mitigation steps include restricting permissions on the cache directory and cache files to prevent unauthorized write access.

• Change the permissions of the cache directory and files to remove world-writable access, for example using: chmod -R o-w /path/to/pachno/cache
• Ensure that only trusted processes have write access to the cache files.

Additionally, consider applying any available patches or updates from the vendor that address this deserialization vulnerability.

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Compliance Impact

The vulnerability allows unauthenticated attackers to execute arbitrary code on the affected system by exploiting deserialization of malicious objects in cache files. This can lead to unauthorized access, data manipulation, or data breaches.

Such unauthorized access and potential data breaches can negatively impact compliance with common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and maintaining system integrity.

Therefore, exploitation of this vulnerability could result in violations of these regulations due to compromised confidentiality, integrity, and availability of data.

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