xyproto Algernon up to 1.17.8 File Extension engine/handlers.go filepath.Ext information disclosure

Summaryinfo

A vulnerability was found in xyproto Algernon up to 1.17.8. It has been declared as problematic. This affects the function filepath.Ext of the file engine/handlers.go of the component File Extension Handler. The manipulation results in information disclosure. This vulnerability is identified as CVE-2026-52792. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in xyproto Algernon up to 1.17.8. It has been classified as problematic. Affected is the function filepath.Ext of the file engine/handlers.go of the component File Extension Handler. The manipulation with an unknown input leads to a information disclosure vulnerability. CWE is classifying the issue as CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. This is going to have an impact on confidentiality. CVE summarizes:

Algernon is a small self-contained pure-Go web server. Prior to 1.17.9, Algernon on Windows selects a file handler in engine/handlers.go by calling filepath.Ext() without first rejecting NTFS-equivalent names such as x.lua::$DATA, x.lua., and x.lua . An unauthenticated client can append one of these suffixes to a public server-side script using the .lua, .tl, .po2, .amber, or .frm extension. The request path passes through URL2filename in utils/files.go, skips the renderer and execution cases, and reaches FilePage, os.Open, ReadAndLogErrors, and ToClient, while NTFS resolves the alias to the underlying script. The server consequently returns raw script source and can expose database credentials, API keys, and the SetCookieSecret value, which may permit forged session cookies. Linux and macOS hosts are not affected by this issue. This issue is fixed in version 1.17.9.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-52792 since 06/08/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1592 by the MITRE ATT&CK project.

Upgrading to version 1.17.9 eliminates this vulnerability.

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Productinfo

Vendor

• xyproto

Name

• Algernon

Version

• 1.17.0
• 1.17.1
• 1.17.2
• 1.17.3
• 1.17.4
• 1.17.5
• 1.17.6
• 1.17.7
• 1.17.8

Website

• Product: https://github.com/xyproto/algernon/

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