CVE-2026-46430: Xyproto Algernon

Medium severity, CVSS 4.3. EPSS: 0.2% chance of exploitation in the next 30 days.

Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, the SSE event server bound to 0.0.0.0:5553 on Linux/macOS by default because the platform-dependent host default in engine/flags.go:39-46 set host = "" for non-Windows, and utils.JoinHostPort("", ":5553") resolves to ":5553". This vulnerability is fixed in 1.17.7.

Affected products

• Xyproto Algernon: before 1.17.7 (fixed in 1.17.7)

Published 2026-05-26. Last modified 2026-07-24.