CVE-2019-11707: in the CISA KEV catalogue
Mozilla Firefox and Thunderbird Type Confusion Vulnerability. CISA added CVE-2019-11707 to the Known Exploited Vulnerabilities catalogue on 2022-05-23 with a default due date of 2022-06-13. Known ransomware campaign use: Unknown. Forensic triage flag: No.
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. (CISA description)
- Vendor / product
- Mozilla Firefox and Thunderbird
- CWE
- CWE-843
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 38%, percentile 98 (scored 2026-11-03)
EPSS puts about 38 in 100 odds (38%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 98% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2019-11707 in the CISA KEV catalogue?
Yes. CISA added CVE-2019-11707 (Mozilla Firefox and Thunderbird Type Confusion Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2022-05-23. CISA's default due date for it is 2022-06-13.
Is CVE-2019-11707 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2019-11707. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2019-11707?
CISA's required action: Apply updates per vendor instructions.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2019-11707