🛡️ CVE-2026-48126
🟠 CVSS 8.2 — High ✅ No Known Exploit CWE-22 NVD
8.2
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Algernon is a small self-contained pure-Go web server. Prior to 1.17.8, when algernon is started with --domain (or --letsencrypt, which silently turns on --domain at engine/flags.go:372), the request handler resolves the served directory by joining the configured --dir with the value of the client-supplied Host header. The join is performed by filepath.Join with no validation, so a Host: .. header walks one level above the document root. Subsequent file resolution then exposes everything in that parent directory — arbitrary file read, full directory listing, and, if any .lua file is present, server-side Lua execution. This vulnerability is fixed in 1.17.8.

Details

Severity HIGH
CVSS Score 8.2
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
CWE CWE-22
Public Exploit ✅ No
Source NVD
Published 2026-05-26
Updated 2026-06-02
Modified 2026-05-26
Fix URL N/A

Affected Packages

Software From version Fixed in
unknown — —

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