Trezor’s firmware is not anti-developer. It permits:
A compromised or malicious web wallet could ask your Trezor to sign a transaction using a non-standard path like m/44'/0'/999999'/0/0 — far outside normal account ranges. The goal: trick you into signing for an address whose private key the attacker knows (e.g., pre-generated from a weak seed). Trezor’s forbidden path check stops this attack cold. trezor forbidden key path
Online forums sometimes suggest: “Just use a different wallet interface that doesn’t check the path.” Trezor’s firmware is not anti-developer
In a perfect world, a user would generate a seed on a Trezor and only use the official Trezor Suite wallet. In this scenario, the wallet software requests keys based on established standards, and the Trezor firmware happily approves the request because it recognizes the path as valid and intended for the user's specific cryptocurrency. Trezor’s forbidden path check stops this attack cold
Last updated: March 2025 – reflects Trezor firmware v24.08+ and Trezor Suite v24.x.
If you force-sign a transaction on a forbidden path, two things can happen:
Some Bitcoin Cash or Dogecoin forks use unusual derivation paths. When you attempt to sign a transaction from such a fork, Trezor sees m/44'/145'/0' (unrecognized coin_type) and blocks it unless the coin’s app is explicitly installed.