CVE-2026-48126
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.
Scoring
- Severity
- HIGH
- CVSS base score
- 8.2
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
- EPSS probability
- 0.34%
- CWE
- CWE-22, CWE-23, CWE-644
- Published
- 2026-05-26
- Last modified
- 2026-05-26
Affected products
- xyproto algernon
Weakness type
Related vulnerabilities
- CVE-2026-15019 — Direct Download for WooCommerce <= 1.19 - Unauthenticated Arbitrary File Read via 'file_id' Path Segment
- CVE-2026-18386 — WP BackItUp Community Edition <= 2.1.0 - Authenticated (Administrator+) Path Traversal to Arbitrary File Read via 'backup_file' Parameter
- CVE-2026-88069 — Path traversal in Pandora archive extractor allows arbitrary file writes outside the extraction directory in pandora analysis
- CVE-2026-53956 — Rattler vulnerable to package cache path traversal via conda package build string
- CVE-2026-86775 — knowns before 0.30.0 Path Traversal via Document API
- CVE-2026-86099 — Chainlit through 2.12.0 Path Traversal via socket.io sessionId
- CVE-2026-78485 — Dell SCG 5.0 Appliance versions prior to 5.36.00.16 and Dell SCG 5.0 Application versions prior to...
- CVE-2026-19729 — Keycloak-services: keycloak-services: incomplete fix for arbitrary filesystem path probing via keystore parameters