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 from endoflife.date and official vendor documentation.
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: Most vulnerability scanners check for known CVEs but do not flag the ongoing accumulation of unpatched vulnerabilities in EOL software versions. Running Claude (Anthropic) Claude Mythos 5.1 past its EOL date creates a permanently growing attack surface that standard security tooling will not surface.
Migrate to Claude (Anthropic) Claude Mythos 5.1 or implement compensating controls — network segmentation, enhanced monitoring, restricted access — while migration is underway.