SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2021-4140

It was possible to construct specific XSLT markup that would be able to bypass an iframe sandbox.

CRITICAL 10.0EPSS 1.34%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (1.34%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a 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.

CVSS 3.1
10.0 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS
1.34% probability · 70th percentile
CISA KEV
Not listed
Weakness
CWE-91
Affected
mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird
Source
security@mozilla.org

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.