SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2021-23999

This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

HIGH 8.8EPSS 1.28%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (1.28%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

If a Blob URL was loaded through some unusual user interaction, it could have been loaded by the System Principal and granted additional privileges that should not be granted to web content. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.

CVSS 3.1
8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS
1.28% probability · 68th percentile
CISA KEV
Not listed
Weakness
CWE-269, CWE-697
Affected
mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird
Source
security@mozilla.org

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