CVE-2026-46430

Algernon: Auto-refresh SSE event server binds to all interfaces by default on Linux/macOS

State: Published
Severity: 4.3 Medium
Published: May 26, 2026
Updated: May 26, 2026
Reserved: May 13, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	4.3 Medium	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N	GitHub_M

Weaknesses

CWE-668 Exposure of Resource to Wrong Sphere
CWE-1188 Insecure Default Initialization of Resource

Affected Products

Product	Versions
algernonxyproto	< 1.17.7Affected

References

https://github.com/xyproto/algernon/security/advisories/GHSA-gj84-924c-48fx

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