Algernon: Auto-refresh SSE event server sets Access-Control-Allow-Origin: *
Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, the SSE event server's Access-Control-Allow-Origin response header was hardcoded to the wildcard * regardless of the caller's Origin. Because EventSource does not preflight and does not send cookies, the wildcard is sufficient to let any third-part…
Severity medium: primary CNA CVSS 4.3 v3.1 (worst CNA-provided scenario) Not listed in this KEV snapshot. Forecast present in this snapshot.
Published 2026-05-26T16:42:40.675Z. Updated 2026-05-26T17:39:14.529Z.