Algernon: Server-side script source disclosure on Windows via NTFS filename (CVE-2026-52792) | HOL Guard CVE

High severityCVE-2026-52792GHSA-MM6C-5J6X-HQ8M

Algernon: Server-side script source disclosure on Windows via NTFS filename

Answer in brief

CVE-2026-52792 records a High severity vulnerability in Algernon: Server-side script source disclosure on Windows via NTFS filename. The current sources do not mark it as known exploited. The current feed maps xyproto/algernon (generic), github.com/xyproto/algernon (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 19, 2026Updated Aug 19, 2026Source checked Aug 19, 2026First seen by HOL Jul 2, 2026Material review Aug 19, 2026

Upstream Advisory

Key facts

Risk: High
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps xyproto/algernon (generic), github.com/xyproto/algernon (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
xyproto/algernongeneric	< 1.17.9	Not reported
github.com/xyproto/algernongo	<=1.17.8	1.17.9

Recommended response

Check inventory. Check lockfiles and deployed manifests for xyproto/algernon, github.com/xyproto/algernon.
Review the reported fix. Update github.com/xyproto/algernon to 1.17.9 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jul 2, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.