{"cve":"CVE-2026-46431","nvd":{"published":"2026-05-26T17:16:51.100","modified":"2026-07-24T11:10:00.170","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N","score":4.3},"cwes":["CWE-942"],"references":["https://github.com/xyproto/algernon/security/advisories/GHSA-hw27-4v2q-5qff","https://github.com/xyproto/algernon/security/advisories/GHSA-hw27-4v2q-5qff"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:36:28.938604137+00:00"},"epss":{"cve":"CVE-2026-46431","score":0.00219,"percentile":0.1244,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-hw27-4v2q-5qff","url":"https://osv.dev/vulnerability/GHSA-hw27-4v2q-5qff","summary":"Algernon: Auto-refresh SSE event server sets Access-Control-Allow-Origin: *","modified":"2026-06-25T23:11:26.240145132Z","packages":[{"ecosystem":"Go","name":"github.com/xyproto/algernon","purl":"pkg:golang/github.com/xyproto/algernon","ranges":["<1.17.7"],"fixed":["1.17.7"]}]},{"id":"GO-2026-5440","url":"https://osv.dev/vulnerability/GO-2026-5440","summary":"Algernon: Auto-refresh SSE event server sets Access-Control-Allow-Origin: * in github.com/xyproto/algernon","modified":"2026-06-25T23:00:17.325837130Z","packages":[{"ecosystem":"Go","name":"github.com/xyproto/algernon","purl":"pkg:golang/github.com/xyproto/algernon","ranges":["<1.17.7"],"fixed":["1.17.7"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}