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CVE-2017-7820
The "instanceof" operator can bypass the Xray wrapper mechanism. When called on web content from the browser itself or an extension the…
Medium5.3EPSS 1.2%
- Published
- Updated
- Reserved
- Assigned by
- mozilla
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.0 | Medium5.3 | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
- EPSS (exploitation in 30 days)
- 1.2% · top 33% of all CVEs (4 Nov 2026)
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The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Weakness
- Xray wrapper bypass with new tab and web console
Affected products
References (4)
- 1039465 (opens in a new tab)vdb-entryx_refsource_SECTRACKx_transferred
- https://bugzilla.mozilla.org/show_bug.cgi?id=1378207 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://www.mozilla.org/security/advisories/mfsa2017-21/ (opens in a new tab)x_refsource_CONFIRMx_transferred
- 101057 (opens in a new tab)vdb-entryx_refsource_BIDx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2017-7820)Record last updated .