Medium severity4.3GHSA Advisory· Published May 26, 2026· Updated May 26, 2026
CVE-2026-46431
CVE-2026-46431
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.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
github.com/xyproto/algernonGo | < 1.17.7 | 1.17.7 |
Affected products
1Patches
Vulnerability mechanics
References
3News mentions
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