Firefox 91 · Version Status
Firefox 91 End of Life Date
Firefox 91 end-of-life date, support status, and CVE risk. Data from endoflife.date and official vendor documentation.
⚠
Firefox 91 is past end of life. This version no longer receives security patches. 1327 days past EOL — migrate to a supported version immediately.
EOL Date
Sep 20, 2022
1327 days past EOL
Latest Release
91.13.0
LTS release
Release Date
Aug 10, 2021
Firefox 91 series
| Version | Latest | EOL Date | Status |
|---|
| 78 LTS |
78.15.0 |
Nov 2, 2021 |
EOL |
| → 91 LTS |
91.13.0 |
Sep 20, 2022 |
EOL |
| 102 LTS |
102.15.1 |
Sep 26, 2023 |
EOL |
| 103 |
103.0.2 |
Aug 23, 2022 |
EOL |
| 104 |
104.0.2 |
Sep 20, 2022 |
EOL |
| 105 |
105.0.3 |
Oct 18, 2022 |
EOL |
| 106 |
106.0.5 |
Nov 15, 2022 |
EOL |
| 107 |
107.0.1 |
Dec 13, 2022 |
EOL |
What does Firefox 91 end of life mean?
When Firefox 91 reaches end of life, the maintainers stop issuing security patches for this version. CVEs discovered after the EOL date are publicly disclosed on the National Vulnerability Database with no patch available. Exploit code frequently appears on GitHub within days of disclosure.
The CVE blind spot: Most vulnerability scanners check for known CVEs but do not flag the ongoing accumulation of unpatched vulnerabilities in EOL software versions. Running Firefox 91 past its EOL date creates a permanently growing attack surface that standard security tooling will not surface.
Migrate to Firefox 150 or implement compensating controls — network segmentation, enhanced monitoring, restricted access — while migration is underway.
Frequently Asked Questions
When does Firefox 91 reach end of life?
Firefox 91 reached end of life on September 20, 2022. This version is no longer receiving security patches.
Is Firefox 91 still supported?
No. Firefox 91 reached end of life on September 20, 2022 and is no longer receiving security patches.
What should I upgrade to from Firefox 91?
The recommended upgrade from Firefox 91 is
Firefox 150 — the latest actively supported version. Check the
Firefox full timeline for all supported versions.
What are the security risks of running Firefox 91 past EOL?
When Firefox 91 reaches end of life, the maintainers stop issuing security patches. Any CVEs disclosed after the EOL date accumulate with no remediation path. Most vulnerability scanners do not flag this — it is the CVE blind spot. Organizations running EOL Firefox should migrate immediately or implement compensating controls.