Pachno 1.0.6 RCE via file upload (CVE-2026-40040)

Overview

A high-severity vulnerability in Pachno version 1.0.6 allows authenticated users to upload malicious files to the server, leading to remote code execution (RCE). The flaw resides in the /uploadfile endpoint, where insufficient file extension filtering can be bypassed.

Vulnerability Details

The vulnerability, tracked as CVE-2026-40040, is an unrestricted file upload flaw. While the application attempts to filter uploaded files by their extension, this protection is ineffective. An attacker with a standard user account can upload arbitrary file types, including .php5 scripts, to directories accessible via the web. Once uploaded, the attacker can directly request the malicious file, causing the server to execute its code. This provides full control over the affected server.

The CVSS v3.1 base score is 8.8 (High). The attack vector is network-based, requires low complexity and low-privilege user credentials, and needs no user interaction.

Impact

Successful exploitation grants an attacker the ability to execute arbitrary commands and code on the underlying server hosting Pachno. This can lead to a complete compromise of the server, data theft, deployment of ransomware, or use of the server as a foothold for further attacks within the network. The requirement for authentication does limit the immediate attack surface, but any compromised user account-even with minimal permissions-can be leveraged for this attack.

Remediation and Mitigation

The primary remediation is to upgrade Pachno to a patched version. Users of version 1.0.6 should immediately check the official Pachno project channels for a security fix and apply the update. If an immediate upgrade is not possible, consider the following temporary mitigations:

• Restrict or monitor access to the /uploadfile endpoint using a web application firewall (WAF).
• Implement strict file upload policies at the server or reverse proxy level, blocking the execution of scripts from the upload directory.
• Conduct a review of the Pachno installation directory for any suspicious files, particularly .php5 or other executable scripts, uploaded recently.

As of this advisory, this vulnerability is not listed in CISA’s Known Exploited Vulnerabilities (KEV) catalog, indicating it is not confirmed to be actively exploited in attacks. However, a proof-of-concept (PoC) exploit is available, raising the risk of future exploitation.

Security Insight

This vulnerability highlights the persistent risk of improper input validation in file handling functions, a common weakness in web applications. It mirrors past incidents in other project management tools where file upload features became a primary vector for server takeover. The presence of a public PoC for an RCE flaw in an open-source project management tool will likely attract opportunistic attackers scanning for unpatched instances, making prompt patching essential. For the latest on data breaches and cybersecurity threats, visit our security news section.

Further Reading

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