Trezor says it has increased the maximum wallet passphrase length from 50 to 128 characters on four devices. The change follows a Coldcard seed-generation flaw that drew attention to both the value and the risks of adding another secret to a wallet.
- The 128-character limit applies to the Model T, Safe 3, Safe 5 and Safe 7.
- The Model One remains limited to 50 characters.
- Users need updated Trezor Suite and compatible device firmware.
- A passphrase adds protection, but losing or mistyping it can make the intended wallet inaccessible.
What a passphrase does
A recovery phrase can restore access to a cryptocurrency wallet. A passphrase is an optional extra secret that combines with the recovery phrase to derive wallet keys. Enter a different passphrase, even by mistake, and the device derives different keys. You’ll open a different wallet, with its own addresses and balances.
A passphrase can make a stolen recovery phrase harder to use. An attacker would also need to know or guess the passphrase. But it is only one layer of defense. A short, predictable or exposed passphrase may offer little protection. If you use both devices, securing a Trezor with Coldcard means handling that extra secret carefully.
There is no reset option. Trezor says it cannot recover a forgotten passphrase, and even a typo can lead to a wallet that appears empty. The original wallet is tied to the exact passphrase used to derive it. A discussion about a potentially hacked Coldcard passphrase is another reminder to treat passphrases as sensitive secrets.
Which Trezor devices support 128 characters?
Trezor says an October software update raised the maximum from 50 to 128 characters on the Model T, Safe 3, Safe 5 and Safe 7. Users need to update both Trezor Suite and compatible device firmware. Devices running older firmware remain subject to the previous limit.
The Model One is not included and remains capped at 50 characters. Trezor’s announcement does not list firmware version numbers, so check the company’s current device documentation before relying on the expanded limit.
Why Trezor cited the Coldcard flaw
Trezor linked the change to a seed-generation flaw in some Coldcard firmware, disclosed in July 2026. The reported vulnerability involved the unpredictability of recovery seeds generated on affected firmware. It was a wallet security issue, not evidence that Bitcoin’s network or consensus rules had been compromised.
Reporting on Coinkite’s guidance says the issue affected seeds generated on vulnerable firmware, not seeds simply imported into an affected device. It also says updating firmware does not fix a seed already generated under vulnerable conditions. Affected users were advised to install corrected firmware, create a fresh seed and move their funds. They should first test the new setup with a small transaction.
The same reporting lists corrected firmware as version 4.2.0 or later for Mk3, 5.6.0 or later for Mk4/Mk5, and 1.5.0Q or later for Coldcard Q. Before taking action, users should confirm their device and recovery steps against Coinkite’s current guidance.
A strong, secret passphrase can add another barrier if a recovery seed is exposed. It does not make a vulnerable seed safe, remove the need to generate a fresh one when advised, or guarantee that funds are protected. Trezor has not provided figures on how many Coldcard users had passphrases or how many were protected by them.
A separate suspected Safe 5 modification
In a separate warning, Trezor said an Indonesian customer reported finding an additional circuit board inside a Safe 5 purchased through former authorized reseller CryptoBilis. Trezor said the suspected modification could potentially collect sensitive information, including recovery phrases. The company reviewed photographs and interviewed the customer but did not physically examine the device.
Trezor reported no confirmed cryptocurrency losses linked to the suspected modification. It advised customers who bought wallets through CryptoBilis from March 2026 onward to move their assets to newly created wallets with fresh recovery phrases. The company said affected customers could request replacement devices or vouchers. Security Alliance’s SEAL 911 response service was assisting with the investigation.
This is a separate, unconfirmed tampering concern, not evidence that Trezor devices are generally compromised. The distinction matters. A reported risk deserves attention, but it is not the same as a confirmed compromise or theft. Trezor has also faced past security scrutiny, including a critical flaw discovered by rival Ledger.
Passphrase and wallet security: key questions
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Which Trezor devices support passphrases up to 128 characters?
The Model T, Safe 3, Safe 5 and Safe 7, with updated Trezor Suite and compatible device firmware.
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Does the Trezor Model One support the expanded limit?
No. It remains limited to 50 characters.
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Can Trezor recover a forgotten passphrase?
No. The exact passphrase is needed to derive the intended wallet. A different entry derives a different one.
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Does a passphrase fix a compromised recovery seed?
No. It can add a barrier if the seed is exposed, but it does not repair the seed or guarantee protection.
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Does updating Coldcard firmware fix a seed created with vulnerable firmware?
No. Reported guidance for affected users was to install corrected firmware, generate a fresh seed and migrate funds.
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Were losses confirmed from the suspected Safe 5 modification?
Trezor reported no confirmed losses and said it had not physically examined the device.
A longer passphrase gives you more room to choose a secret that is difficult to guess. It also gives you another piece of information to preserve exactly. Before using one with meaningful funds, make sure you understand how your wallet derives accounts and can reliably reproduce the passphrase. Extra security only helps if you can still access the wallet it protects.
