Trezor Raises Wallet Passphrase Limit From 50 to 128 Characters
Trezor now allows wallet passphrases of up to 128 characters, up from 50, on Model T and Safe devices with updated firmware. The company tied the change to July's Coldcard thefts, where strong passphrases protected some users whose recovery phrases were exposed.
Optional passphrases on Trezor hardware wallets can now run to 128 characters, up from 50, under a change the company announced on November 1.
The longer limit ships in the October Trezor Suite update, announced in a blog post titled "Trezor Suite update October 2026," and requires compatible device firmware. Devices on older firmware keep the 50-character limit. Supported devices are the Model T, Safe 3, Safe 5 and Safe 7. The older Model One stays at 50 characters.
A passphrase works alongside the recovery phrase. An attacker who obtains only the recovery phrase would still need the exact passphrase to reach the funds. Each passphrase opens a separate wallet.
Response to the Coldcard thefts
Trezor tied the change to the July attacks on Coldcard users. A firmware flaw in Coldcard produced recovery phrases with insufficient randomness, which attackers could reconstruct. Trezor said strong, unique passphrases protected some affected users.
Effective randomness in the affected phrases fell from about 128 bits to 40 bits, according to reports on the incident. On July 31, about 594 BTC (about $38 million) was stolen from around 500 wallets within 25 minutes. By August 12, estimates reached about $116 million across more than 5,200 addresses, and reported Coldcard-related losses have been put above $100 million.
Coldcard released updated firmware and, in August, added randomness requirements for new seeds, using keyboard activity, dice rolls or coin flips. Fixed firmware does not repair phrases created on vulnerable versions.
Limits of the fix
Trezor says wallets originally generated on its devices were not affected by the Coldcard flaw. Users who restored a vulnerable Coldcard-generated phrase on a Trezor remain exposed until they move funds to a newly generated wallet. A longer passphrase does not change that.
Trezor also cautions that passphrases are an advanced feature. A typo opens a different wallet, and Trezor cannot recover a lost passphrase, so a forgotten one can lock users out permanently. The company publishes a guide explaining passphrases.
The update comes two days after a separate security notice: on October 30, Trezor advised buyers from former reseller CryptoBilis to move funds after an Indonesian customer reported a suspected implant in a Safe 5. Trezor had not examined that device and reported no confirmed losses.
