CVE-2026-46431 (GCVE-0-2026-46431)

Vulnerability from cvelistv5 – Published: 2026-05-26 16:42 – Updated: 2026-05-26 17:39
VLAI
Title
Algernon: Auto-refresh SSE event server sets Access-Control-Allow-Origin: *
Summary
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.
Severity
4.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-26 17:38 UTC
CWE
  • CWE-942 - Permissive Cross-domain Policy with Untrusted Domains
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7615 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
xyproto algernon Affected: < 1.17.7
guessed Create a notification for this product.
Show details on NVD website
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