Claude (Anthropic) Claude Mythos 5.1 End of Life Date
Claude (Anthropic) Claude Mythos 5.1 end-of-life date, support status, and CVE risk. Data reconciled from official vendor documentation and endoflife.date at every build; the source of each date is on the product page.
Claude (Anthropic) claude-mythos-5-1 was released on September 1, 2026 and has no published end-of-life date yet.
| Version | Latest | EOL Date | Status |
|---|---|---|---|
| Claude 1.0 | — | Nov 6, 2024 | EOL |
| Claude Instant 1.0 | — | Nov 6, 2024 | EOL |
| Claude 1.1 | — | Nov 6, 2024 | EOL |
| Claude 1.2 | — | Nov 6, 2024 | EOL |
| Claude Instant 1.1 | — | Nov 6, 2024 | EOL |
| Claude 1.3 | — | Nov 6, 2024 | EOL |
| Claude 2.0 | — | Jul 21, 2025 | EOL |
| Claude Instant 1.2 | — | Nov 6, 2024 | EOL |
What does Claude (Anthropic) Claude Mythos 5.1 end of life mean?
When Claude (Anthropic) Claude Mythos 5.1 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: A CVE-based scan does not show the ongoing accumulation of unpatched vulnerabilities in EOL software versions. Some scanners flag unsupported versions of common products, but coverage varies, and none of them give you the date in advance. Running Claude (Anthropic) Claude Mythos 5.1 past its EOL date creates a growing attack surface that a clean scan result does not rule out.
Migrate to Claude (Anthropic) Claude Haiku 5.5 or implement compensating controls — network segmentation, enhanced monitoring, restricted access — while migration is underway.