CVE-2026-46431

Published: May 26, 2026Modified: Jul 24, 2026Deferred

4.3

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Exploitability: 2.8 / Impact: 1.4

Source: security-advisories@github.com (Secondary)

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.

Related CWEs

CWE-942

Permissive Cross-domain Policy with Untrusted Domains

The product uses a cross-domain policy file that includes domains that should not be trusted.

References (2)

https://github.com/xyproto/algernon/security/advisories/GHSA-hw27-4v2q-5qff

Source: security-advisories@github.com

https://github.com/xyproto/algernon/security/advisories/GHSA-hw27-4v2q-5qff

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

Timeline

No history available yet.