How to check if you are exposed to CVE-2019-17026
- Find every Mozilla Firefox and Thunderbird system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
- Compare each version with the fixed versions in the vendor advisory. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
- Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2019-17026.
US federal agencies had to fix this by 2022-05-03. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.
Affected versions
Versions the National Vulnerability Database lists as vulnerable to CVE-2019-17026. Check the vendor advisory for the exact fixed builds before you sign anything off.
| Product | Vulnerable versions |
|---|---|
| Mozilla Firefox | before 68.4.1; before 72.0.1 |
| Mozilla Thunderbird | before 68.4.1 |
| Canonical Ubuntu Linux | 16.04 |
Timeline
- · Published in the National Vulnerability Database
- · Added to CISA's Known Exploited Vulnerabilities catalog, 611 days after it was published
- · Fix-by date for US federal agencies, passed 1,643 days ago
Weakness type
More exploited Mozilla vulnerabilities
CISA lists 13 exploited Mozilla vulnerabilities. The closest matches:
- CVE-2019-11708Mozilla Firefox and Thunderbird Sandbox Escape VulnerabilityAdded 2022-05-23
- CVE-2019-11707Mozilla Firefox and Thunderbird Type Confusion VulnerabilityAdded 2022-05-23
- CVE-2013-1690Mozilla Firefox and Thunderbird Denial-of-Service VulnerabilityAdded 2022-03-28
- CVE-2020-6820Mozilla Firefox And Thunderbird Use-After-Free VulnerabilityAdded 2021-11-03
- CVE-2020-6819Mozilla Firefox And Thunderbird Use-After-Free VulnerabilityAdded 2021-11-03
- CVE-2010-3765Mozilla Multiple Products Remote Code Execution VulnerabilityAdded 2025-10-06
- CVE-2024-9680Mozilla Firefox Use-After-Free VulnerabilityAdded 2024-10-15
- CVE-2016-9079Mozilla Firefox, Firefox ESR, and Thunderbird Use-After-Free VulnerabilityAdded 2023-06-22
Keep going
Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.