{"cve":"CVE-2017-7820","nvd":{"published":"2018-06-11T21:29:10.873","modified":"2026-06-17T01:25:16.797","status":"Modified","description":"The \"instanceof\" operator can bypass the Xray wrapper mechanism. When called on web content from the browser itself or an extension the web content can provide its own result for that operator, possibly tricking the browser or extension into mishandling the element. This vulnerability affects Firefox < 56.","cvss_v4":null,"cvss_v3":{"version":"3.0","vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","score":5.3},"cwes":[],"references":["http://www.securityfocus.com/bid/101057","http://www.securitytracker.com/id/1039465","https://bugzilla.mozilla.org/show_bug.cgi?id=1378207","https://www.mozilla.org/security/advisories/mfsa2017-21/","http://www.securityfocus.com/bid/101057"],"products":["mozilla:firefox"],"source":"nvd","synced_at":"2026-10-19T20:51:47.459859389+00:00"},"epss":{"cve":"CVE-2017-7820","score":0.01163,"percentile":0.67261,"date":"2026-10-31"},"kev":null,"osv":[],"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."]}