CVE-2026-46431 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 ...

CVE-2026-46431

CVE-2026-46431 affects Algernon’s SSE event server prior to version 1.17.7, where Access-Control-Allow-Origin was hardcoded to “*”. This allowed cross-origin EventSource connections to read the live filename stream, compromising confidentiality. The issue is fixed in 1.17.7; upgrading to that ver...