In August 2026, the Ethereum (ETH) development team released a roadmap that moves beyond hash‑based signatures toward a stronger post‑quantum proof‑of‑work system. The new direction focuses on two core technologies—“leanXMSS” and “leanVM”—instead of “Poseidon.” While the official roadmap targets 2029, it notes that timing may vary.
The Post‑Quantum page proposes replacing BLS signatures with leanXMSS (Lean eXtended Lightweight Signature Scheme) and a multi‑layer structure that separates data from execution layers. In particular, “leanVM” is a minimal zero‑knowledge virtual machine that reduces proof costs and enables the use of new hash functions. The team states users need not move wallets or take additional steps; existing user experience should remain largely unchanged.
Whether Poseidon fails remains unconfirmed officially, but the Poseidon Cryptanalysis Initiative (PCI) concluded in 2024–2026 that high‑cost hash functions are sufficiently secure. That analysis was scheduled for a “second‑phase termination point” in December 2026, and no final decision to retire Poseidon has been made yet. Ethereum’s community notes that adopting new hash functions effectively moves the proof‑of‑work roadmap toward post‑quantum conversion.
Such changes matter more than price volatility; from an infrastructure risk perspective they are significant. From a Korean investor’s view, although the “fork schedule” and final design are not set, post‑quantum conversion is expected to raise security levels. Ethereum stresses that the priority is post‑quantum security and protocol simplification rather than whether Poseidon is retired, and the industry focuses on new hash‑function potential in research competition.