CVE-2026-48126: Algernon: Host header path traversal in --domain mode reads files and runs Lua from parent dir
xyproto · algernon
Affected: xyproto algernon · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 27% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- xyproto · algernon< 1.17.8
On the Atlas
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CoverageNo articles yet
No CyberSIXT article names CVE-2026-48126 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.