CVE-2017-7820: mozilla firefox
Vulnerability summary
CVE-2017-7820 is a medium (CVSS 5.3) vulnerability in mozilla firefox. EPSS estimates a 1.16% chance of exploitation in the next 30 days, higher than 66.7% of scored vulnerabilities. 1 public exploit is recorded.
Advisory lineage
Upstream 0 · Downstream 3 · Related 3Timeline
- 11-06-2018PublishedVulnerability first disclosed.
- 05-08-2024Last modifiedVulnerability information updated.
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 metrics
3 scores · 2 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated5.3MediumCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS trend
Probability
1.16%
Chance of exploitation in the next 30 days
Percentile
67%
Versus all other CVEs
30-day change
-0.03 pp
From 1.19% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
1 foundExploit Reference (bugzilla.mozilla.org)
Maturity: unknown
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Mozilla1 product
- firefox≥ unspecified, < 56 | ≤ 55.0.3
Ubuntu1 product
- firefox< 56.0+build6-0ubuntu0.14.04.1 | < 56.0+build6-0ubuntu0.16.04.1 | < 56.0+build6-0ubuntu1
2 vendors · 2 products