CVE-2021-4140

Public Exploit

Description

It was possible to construct specific XSLT markup that would be able to bypass an iframe sandbox. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

Category

10.0
CVSS
Severity: Critical
CVSS 3.1 •
EPSS 0.07%
Vendor Advisory mozilla.org Vendor Advisory mozilla.org Vendor Advisory mozilla.org Vendor Advisory mozilla.org
Affected: Mozilla Firefox ESR
Affected: Mozilla Firefox
Affected: Mozilla Thunderbird
Published at:
Updated at:

References

Link Tags
https://www.mozilla.org/security/advisories/mfsa2022-01/ vendor advisory
https://www.mozilla.org/security/advisories/mfsa2022-02/ vendor advisory
https://www.mozilla.org/security/advisories/mfsa2022-03/ vendor advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1746720 patch exploit vendor advisory issue tracking

Frequently Asked Questions

What is the severity of CVE-2021-4140?
CVE-2021-4140 has been scored as a critical severity vulnerability.
How to fix CVE-2021-4140?
To fix CVE-2021-4140, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-4140 being actively exploited in the wild?
It is possible that CVE-2021-4140 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-4140?
CVE-2021-4140 affects Mozilla Firefox ESR, Mozilla Firefox, Mozilla Thunderbird.
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