CVE-2026-52792 Algernon: Server-side script source disclosure on Windows via NTFS filename
Unauthenticated attackers can retrieve raw source code of server-side scripts on Windows by exploiting NTFS filename aliases, potentially exposing credentials and session secrets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-52792?
CVE-2026-52792 is a high-severity vulnerability in xyproto algernon, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-69
Which versions are affected by CVE-2026-52792?
3 open source packages ship an affected version, including github.com/xyproto/algernon.
| Package | Affected | Fixed in |
|---|---|---|
github.com/xyproto/algernon Go | All versions | 1.17.9 |
github.com/xyproto/algernon Go | All versions | 1.17.9 |
github.com/xyproto/algernon Go | All versions | 1.17.9 |
How do I fix CVE-2026-52792?
Upgrade github.com/xyproto/algernon to 1.17.9 or later.
Is CVE-2026-52792 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-52792 exists.
Sources
Also known as GHSA-mm6c-5j6x-hq8m, GO-2026-5903.