cve.bz

CVE-2026-46431

4.3 mediumEPSS 0.2%

Medium (4.3). EPSS 0.2% chance of exploitation in the next 30 days. Fixed in github.com/xyproto/algernon 1.17.7.

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

CVSS 3.1

4.3 medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
EPSS
0.2% chance of exploitation in the next 30 days; higher than 12% of CVEs (scores of 2026-10-31)
CWE
CWE-942
Published
Modified
Record from
the NVD, synced

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-hw27-4v2q-5qffGogithub.com/xyproto/algernon<1.17.71.17.7
GO-2026-5440Gogithub.com/xyproto/algernon<1.17.71.17.7

References

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