CVE-2026-46430CWE-1188CWE-668

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

Medium · published May 26, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
13.4
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00233 · 13.4th percentile
Weaknesses
CWE-1188 · Initialization of a Resource with an Insecure Default; CWE-668 · Exposure of Resource to Wrong Sphere
Published
2026-05-26T16:41Z
EPSS history
Timeline
  • 26 MAY 16:41Z
    Algernon: Auto-refresh SSE event server binds to all interfaces by default on Linux/macOS
    cvelistv5