Mozilla Firefox and Thunderbird Type Confusion Vulnerability

Added to KEV
2022-05-23
Federal due date
2022-06-13
Vendor
Mozilla
Product
Firefox and Thunderbird
EPSS
99.3th percentile (score 0.843, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Unknown
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2019-11707

CISA short description

Mozilla Firefox and Thunderbird contain a type confusion vulnerability that can occur when manipulating JavaScript objects due to issues in Array.pop, allowing for an exploitable crash.

Required action

Apply updates per vendor instructions.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.