Algernon vulnerable to server-side script source disclosure on Windows via NTFS filename

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-52792: 0.63% estimated exploitation activity in the next 30 days; percentile 50.16 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Algernon selects its file handler from filepath.Ext() (engine/handlers.go:134), which does not treat the NTFS-equivalent names x.lua::$DATA, x.lua., or x.lua as .lua. On Windows, an unauthenticated client appends one of these suffixes to any server-side script on a public path and receives its raw source instead of executed output, leaking embedded secrets such as database credentials and the SetCookieSecret value. Linux and macOS hosts are unaffected. Preconditions - Algernon runs on a Windows host (NTFS filesystem). - The instance serves at least one server-side script (.lua, .tl, .po2, .amber, .frm). - The script sits on a public path, or no auth backend is configured (--nodb, --simple, or default no-DB). - HTTP/HTTPS reachability to the server. Details The request path reaches FilePage through URL2filename (utils/files.go:24), which rejects only ..; a :, a trailing ., and a trailing space all pass through into filename. filepath.Ext does an exact suffix match, so…

Published by the source

2 Jul 2026, 20:46 UTC

Last modified by the source

2 Jul 2026, 20:46 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-mm6c-5j6x-hq8m

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# Patch Next advisory brief: CVE-2026-52792

Advisory: Algernon vulnerable to server-side script source disclosure on Windows via NTFS filename
IDs: CVE-2026-52792, GHSA-mm6c-5j6x-hq8m
Record: https://patchnext.com/advisories/cve-2026-52792 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/xyproto/algernon 1.17.9. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/xyproto/algernon: affected <= 1.17.8; fixed in 1.17.9

## Suggested inspection (read-only)
- Go github.com/xyproto/algernon: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/xyproto/algernon.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-mm6c-5j6x-hq8m (GitHub-reviewed advisory GHSA-mm6c-5j6x-hq8m lists affected ranges: Go github.com/xyproto/algernon >=0 <=1.17.8)

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