VULNERABILITY INTELLIGENCE

CVE-2026-46431

CVSS score4.3 MEDIUM
EPSS probability0.22%
CISA KEVNot currently listed
Published2026-05-26
Last modified2026-07-24
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Description

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-party page the developer visits open a cross-origin EventSource to the SSE port and read the live filename stream from JavaScript. This vulnerability is fixed in 1.17.7.

Weakness classification

  • security-advisories@github.com: CWE-942

Primary references