Knockout.js End of Life (EOL) Dates & Support Timeline
Complete end-of-life dates, support windows, and security status for all Knockout.js versions. Data sourced from endoflife.date and official vendor documentation. Updated at every deploy.
| Version | Latest Release | Release Date | EOL Date | Days | Status |
|---|---|---|---|---|---|
| 3.0 | 3.3.0 | Oct 25, 2013 | Nov 17, 2015 | 3886 days past EOL | EOL |
| 3.4 | 3.4.2 | Nov 17, 2015 | Feb 21, 2019 | 2694 days past EOL | EOL |
| 3.5 | 3.5.3 | Feb 21, 2019 | TBD | Supported | Active |
Knockout.js lifecycle status — the real story
Knockout.js was a pioneering MVVM framework of the early 2010s, and it occupies an unusual lifecycle position: not formally end-of-life, but functionally finished. The 3.5 line released in February 2019 remains the only maintained branch, receiving rare compatibility patches (3.5.3 arrived in March 2026) with no feature development for years.
Roughly 110,000 weekly npm downloads and a long tail of enterprise line-of-business apps — especially older ASP.NET applications where Knockout shipped in the default templates — keep it in production far beyond its ecosystem's lifespan. Versions before 3.5 should be treated as unsupported.
The practical risk is less about Knockout CVEs and more about ecosystem decay: modern build tooling, TypeScript typings, and security tooling increasingly assume frameworks Knockout predates, which raises the cost of every year of deferral.
What does Knockout.js end of life mean for your organization?
When a version of Knockout.js reaches end of life, the maintainers stop issuing security patches. Vulnerabilities discovered after this date are publicly disclosed on the National Vulnerability Database, exploit code appears on GitHub, and your systems remain permanently exposed.
The CVE blind spot: Most vulnerability scanners check for known CVEs but do not flag the accumulation of unpatched vulnerabilities in EOL software. With a zero-day, nobody knows about the vulnerability. With EOL software, the vulnerability is public — listed, rated, and often weaponized — but no patch will ever exist. This is the most dangerous gap in enterprise security posture.
Organizations running EOL Knockout.js should treat it as a vulnerability class in their risk register, apply compensating controls (network segmentation, enhanced monitoring, access restriction), and prioritize migration to a supported version.
Extended Support Options
If you cannot migrate immediately, extended support vendors provide continued security patches for EOL Knockout.js versions. This is a bridge, not a permanent solution — plan your migration in parallel.
We work with vetted extended support vendors. Tell us what you need and we'll connect you with the right provider.
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