CVE-2026-6105: perfree go-fastdfs-web Improper Authorization - PoC Available

Vendor-confirmed - CVE-2026-6105 is a high severity improper authorization in perfree go-fastdfs-web up to 1.3.7 that lets remote attackers bypass authentication and compromise the application by exploiting the unprotected doInstall interface. PoC code is public and no vendor patch is available.

Overview

A high-severity improper authorization vulnerability (CVE-2026-6105) exists in perfree go-fastdfs-web versions up to and including 1.3.7. The flaw resides in the doInstall interface within the src/main/java/com/perfree/controller/InstallController.java file. This interface fails to properly enforce access controls, allowing remote attackers to bypass intended authorization mechanisms.

Technical Details

The vulnerability is network-based (Attack Vector: NETWORK) and requires no user interaction or prior privileges to exploit (Privileges Required: NONE, User Interaction: NONE). Its low attack complexity means exploitation is straightforward. While the exact manipulation of the doInstall interface is not detailed here, a proof-of-concept (PoC) exploit has been made publicly available, significantly increasing the risk of attempted attacks. The vendor was contacted prior to disclosure but did not respond.

Impact

Successful exploitation could allow an unauthenticated remote attacker to perform unauthorized actions. The specific impact depends on the functionality exposed by the vulnerable doInstall interface, which could range from unauthorized configuration changes to a complete compromise of the application’s integrity. Organizations using the affected software could face data manipulation, service disruption, or further system compromise.

Remediation and Mitigation

As the vendor has not provided a patch, users must implement immediate mitigations.

• Primary Action: If possible, upgrade to a version of go-fastdfs-web later than 1.3.7 if and when the vendor releases a fix. Monitor the project’s official channels for updates.
• Network Controls: Restrict network access to the go-fastdfs-web management interface. Use firewall rules or network security groups to allow access only from trusted, necessary administrative IP ranges.
• Compensating Controls: Implement a Web Application Firewall (WAF) with rules designed to detect and block unauthorized access attempts to installation or setup endpoints.

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Security Insight

This vulnerability highlights the persistent risk in administrative and setup interfaces, which are often overlooked during security hardening. The lack of vendor response to a disclosed PoC creates a prolonged window of exposure for users, shifting the entire burden of defense onto the implementing organization. This pattern mirrors past incidents in open-source projects where maintainer unresponsiveness has forced communities to rely on forks or workarounds for security.

Further Reading

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