CVE-2017-7820

firefox: The "instanceof" operator can bypass the Xray wrapper mechanism

CVE-2017-7820 is fixed in 4 products on 1 platform, first by firefox 56.0+build6-0ubuntu1, released October 1, 2017. It is not reported as exploited. Patch Radar priority: Routine.

Routine
CVSS
n/a
Low
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0116
67th percentile

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.

Where it's fixed

ProductFixed inFixReleased
Linux
firefox · Ubuntu 18.04.6 LTS (bionic) 56.0+build6-0ubuntu1 firefox 56.0+build6-0ubuntu1 Oct 1, 2017
firefox-globalmenu · Ubuntu 18.04.6 LTS (bionic) 56.0+build6-0ubuntu1 firefox-globalmenu 56.0+build6-0ubuntu1 Oct 1, 2017
firefox-mozsymbols · Ubuntu 18.04.6 LTS (bionic) 56.0+build6-0ubuntu1 firefox-mozsymbols 56.0+build6-0ubuntu1 Oct 1, 2017
firefox-testsuite · Ubuntu 18.04.6 LTS (bionic) 56.0+build6-0ubuntu1 firefox-testsuite 56.0+build6-0ubuntu1 Oct 1, 2017

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