Trezor raises passphrase limit to 128 characters following Coldcard wallet exploits
Hardware wallet maker Trezor has expanded its passphrase limit from 50 to 128 characters across most models, citing the summer Coldcard seed flaw that exposed wallets to more than $100 million in thefts.
Trezor has expanded its passphrase limit to 128 characters, up from the previous 50-character cap, according to its Nov. 1 Trezor Suite update announcement. The expanded limit requires the latest Trezor Suite application alongside a device firmware update, while older firmware and the entry-level Model One will remain capped at 50 characters. Per Trezor's documentation, the longer passphrases are supported on the Model T, Safe 3, Safe 5, and Safe 7.[1][2][3]
Trezor framed the upgrade around the seed generation vulnerability on Coldcard devices that triggered a wave of wallet thefts starting in late July. A firmware flaw from March 2021 compromised the randomness of certain Coldcard backups, allowing attackers to rebuild weak seeds offline. However, users who secured their wallets with strong, unique BIP-39 passphrases were shielded from the attacks because accessing the funds required cracking both the seed and the passphrase.[1][4]
The Coldcard exploit resulted in substantial losses, with Galaxy Research estimating on Aug. 3 that approximately 1,596 BTC had been stolen from roughly 7,300 addresses, putting damages above $100 million. Trezor clarified that its own hardware was never vulnerable to the flaw, though users who previously generated seeds on a Coldcard and restored them onto a Trezor were advised to migrate their funds. Trezor also warned that passphrases remain an advanced security feature, noting that mistyping or forgetting one will cause irreversible loss of funds.[1][4]
Key facts
- Trezor increased its wallet passphrase ceiling from 50 to 128 characters on supported devices.
- The Model T, Safe 3, Safe 5, and Safe 7 support the 128-character limit, while the Model One keeps its 50-character cap.
- Using the extended passphrase requires the newest Trezor Suite app and updated device firmware.
- Trezor cited the July Coldcard seed generation attacks, which allowed attackers to compromise weak seeds, as the reason for the update.
- Galaxy Research estimated on Aug. 3 that the Coldcard exploits resulted in the theft of about 1,596 BTC across 7,300 addresses, exceeding $100 million in losses.
- Trezor noted that its own devices were unaffected by the Coldcard bug, but advised moving funds if a wallet was originally generated on a Coldcard.
Sources · 4 sources
- UN
UnchainedArticle ·
Trezor Now Accepts 128-Character Passphrases, Pointing to Coldcard’s Seed Flaw Most Trezor wallets can now take a passphrase of up to 128 characters , up from the old cap of 50 , the hardware wallet maker announced in its Nov. 1 Trezor Suite update post. The longer limit requires the newest Suite app plus a firmware update on the device, and Trezor said older firmware “will still have a 50-character limit.” Trezor put the change in the context of the Coldcard thefts that began in late July. Its post said a firmware flaw left some Coldcard backups with far less randomness than intended, and that users “with a strong, unique passphrase were protected” because “an attacker needed both the weak backup and the passphrase to reach their wallet.” Trezor said the question it then kept hearing was whether a longer passphrase was possible. Get Unchained’s crypto news in your inbox with the free Unchained Daily newsletter . How the Coldcard Seeds Failed Galaxy Digital’s head of research, Alex Thorn , traced the problem to an older firmware change. “Coldcard had updated their firmware on March 17th, 2021 to add their own version of a random number generator,” Thorn said on Unchained’s Bits + Bips in early August, adding that “they miswired it into the firmware.” Coinkite, the company behind Coldcard, has described the cause as a build and link error from that March 2021 migration, which left seed generation running on a general-purpose software generator instead of the device’s hardware one. Attackers then rebuilt the weak seeds offline, Coinkite said. Galaxy Research estimated on X on Aug. 3 that about 1,596 BTC had been taken from roughly 7,300 addresses across three confirmed waves plus 14 smaller incidents, putting losses above $100 million . Unchained later reported that Thorn was tracking a suspected fourth wave. Why Passphrase Length Matters A BIP-39 passphrase, added on top of the seed, opens a separate wallet with its own addresses. That means an attacker who reconstructs a weak seed still has to guess the passphrase before reaching the funds. Coinkite’s guidance put affected wallets at risk unless the seed was created with at least 50 independent, private dice rolls or the wallet carried a strong, unique passphrase, warning that a “short, common, patterned, quoted, reused, exposed, or uncertain passphrase does not qualify.” At least one short passphrase reportedly did not hold. On Aug. 2, the X account BTC Sessions reported on X what it called the first confirmed loss of “a Mk3 + 2 Word Passphrase.” Trezor wrote in an August post that cracking tools work through dictionary words, leaked passwords and patterns, and that “length alone doesn’t guarantee entropy.” Which Trezor Devices Get It Per Trezor’s guide, the Model T, Safe 3, Safe 5 and Safe 7 all support the longer passphrases; the Model One keeps its 50-character maximum. The changelog for core firmware 2.13.0 , dated Oct. 21, describes the new ceiling as “128 bytes,” while Trezor’s post and guide count it in characters. The October release notes list the feature in Suite 26.10.3 on desktop and 26.10.2 for the mobile app, and say updates roll out in stages. Trezor said in August that its own devices were not affected by the Coldcard flaw, though wallets first created on a Coldcard and later restored on a Trezor should be moved. The passphrase update comes days after Trezor said it was treating as credible a report of an implanted Safe 5 sold by former reseller CryptoBilis. Trezor’s post also called the passphrase “an advanced feature” and warned that a mistyped or forgotten one can mean lost funds. Related Listen: Bits + Bips: Is Any Cold Wallet Safe? Inside the Coldcard Hack’s Wave Three The post Trezor Now Accepts 128-Character Passphrases, Pointing to Coldcard’s Seed Flaw appeared first on Unchained .
Open source - CN
crypto.news@cryptodotnewsPost on X ·
JUST IN: Trezor raises wallet passphrase limit to 128 characters after Coldcard exploits The update follows attacks that exposed weaknesses in recovery phrases. https://t.co/3I5SvTlMkd
Open source - LS
Laura Shin@laurashinPost on X ·
Trezor's longer passphrase limit needs both a Trezor Suite update and new device firmware. Trezor says the Model One keeps its 50-character maximum. https://t.co/nKzSJO0ZCT
Open source - CT
Coin TelegraphArticle ·
Trezor lifts password ceiling after Coldcard’s $100M wallet thefts Trezor cited July’s Coldcard attacks, in which strong passphrases helped protect some users whose wallet recovery information was compromised.
Open source