COLDCARD

Coinkite, the maker of COLDCARD, was founded in Toronto, Canada, in 2012. Co-founders Rodolfo Novak and Peter Gray came across the Bitcoin white paper in 2011 and later built a rudimentary bitcoin hardware wallet. Coinkite initially offered developer tools such as API and wallet products; in March 2016 the company announced it would shut down its web wallet over 30 days and focus on hardware, with then-CEO Novak saying the company wanted “to write software, not deal with lawyers and DDoSing.”⁠[1][2][3][3][3][3][3]

On December 8, 2017, Coinkite announced the Coldcard bitcoin hardware wallet and opened pre-orders, with the first units planned to ship in the second quarter of 2018; it launched the X (then Twitter) account @COLDCARDwallet the same day. Coinkite pitched it as an open, cheap and ultrasecure hardware wallet: it is based on BIP39 seed words, needs no companion app on the computer, allows fully offline signing by passing transactions on a MicroSD card, and runs open-source software written in MicroPython.⁠[4][4][4][5][4][4][4][4][4]

The first device stored the master secret in Microchip’s ATSHA204 secure chip rather than in the main processor, so that an attacker would have to know the PIN to extract the key. It offered an optional “secondary PIN” that opened a separate wallet to limit losses under duress, and its firmware was signed with a factory key, with a green or red light at start-up showing whether the firmware was genuine. The Mk line of hardware wallets was introduced from 2018 onward.⁠[4][4][4][4][4][4][4][4][2]

In December 2018, researchers at the CCC security conference demonstrated attacks on Trezor and Ledger hardware wallets under the name wallet.fail. Although Coldcard was not mentioned, Coinkite published a response explaining its own approach: rather than relying on tamper stickers, it ships each device in a uniquely serialized bag whose number is permanently recorded in the device and checked by the customer on delivery, and its clear plastic case is part of its protection. Coinkite also criticized researchers for disclosing major vulnerabilities without first contacting the vendor, and said the company did not pay bug bounties but was happy to discuss security issues with researchers by encrypted email.⁠[6][6][6][6][6][6][6][6]

In January 2019, researcher Lazy Ninja coordinated the disclosure of an invasive man-in-the-middle attack that could falsify some secure-chip responses and bypass PIN-attempt delays, making short PINs brute-forceable; Coinkite hardened the device through bootrom 1.1.0 and the Mk2 circuit board design. On August 7, researcher Christian Reitter published a side-channel issue in which OLED screen power consumption might leak displayed content; Coinkite added precautionary mitigations in firmware 2.1.2 but called the issue “unproven” and “completely impractical.”⁠[7][7][7][8][8][8]

On August 26, 2019, Coinkite announced the Coldcard Mark 3 (Mk3): the secure chip was changed to the ATECC608A, the device bricks itself after 13 wrong PIN attempts under a policy enforced entirely by the secure chip, the main processor was upgraded to the STM32L496RGT6 with 320 KiB of memory, and the hardware was hardened against side-channel attacks; the earlier secondary wallet feature was dropped because of limitations in the secure chip, with BIP39 passphrases recommended instead. That October, Coinkite published the Mk3’s schematic and bill of materials so security researchers could build and analyze one from off-the-shelf parts.⁠[9][9][9][9][9][9][9][9][10][10][10]

On December 19, 2019, Coinkite released firmware 3.0.6, fixing a multisig change-script parsing issue reported by researcher Dmitry Petukhov in which appended script operations could make an attacker-controlled multisig output pass as wallet change; Coinkite said it had found no evidence of exploitation.⁠[7][7][7]

On May 18, 2020, Ledger’s security lab Donjon published a report demonstrating laser fault injection to read protected data from the ATECC508A secure chip used in the Coldcard Mk2, which combined with material in the main chip allowed PIN recovery. Coinkite responded that the research did not affect the Mk3 then on sale and called Donjon the most professional security researchers in the Bitcoin space; it noted that the attack required desoldering the chip, removing its packaging and grinding the silicon with laser equipment costing about $200,000, and said only nation-state-like actors could plausibly carry it out.⁠[11][7][11][11][11][11][11][11][11]

In June that year, Coinkite released two accessories: Coldpower, which powers a wallet from a 9-volt battery instead of a computer, and Seedplate, a metal plate for engraving seed words. Novak said the company wanted to protect people from “bad USB” attacks by making air-gapped use easier.⁠[12][12][12]

On November 23, 2020, Coldcard released beta firmware fixing a flaw found by Shift Crypto security researcher Ben Ma, in which an attacker could disguise a Bitcoin mainnet transaction as a testnet transaction to trick users into signing it. Ma reported it to Coinkite on August 4 under an agreed 90-day embargo. A Coinkite representative said the attack was unrealistic because the attacker would have to convince the victim to manually switch the device to testnet; after the fix, switching to testnet shows a warning.⁠[13][13][13][7][13][13][13]

On February 9, 2021, Coinkite recommended that users update to firmware 3.2.2 because of a multisig flaw privately reported in November 2020 by researchers Hugo Nguyen and Marko Bencun of Shift Crypto: when registering a multisig wallet, Coldcard did not require one of the extended public keys to belong to the device itself, allowing a compromised coordinator to substitute attacker-controlled keys. The issue was fixed before publication.⁠[14][7][7][7]

On January 23, 2022, Coinkite opened early-bird reservations for the COLDCARD Mk4, which added a USB-C connector, NFC, memory with no transaction size limit and a dual secure chip design from different vendors; the Mk4 was released that February and by early 2023 was Coinkite’s best-selling product. Before launch, Coinkite paid Lazy Ninja to review the Mk4’s PIN derivation, attempt limits and random-number generation, and adopted the key recommendations before firmware 5.0.0.⁠[15][15][15][2][2][7][7]

On February 9, 2023, Coinkite opened early-bird reservations for the COLDCARD Q1, which has a full QWERTY keyboard, a color LCD screen with nine times the pixels of the Mk4, an LED-lit QR code scanner and two MicroSD slots, runs on USB-C or three AAA batteries, and allows USB and NFC data to be permanently disabled by cutting circuit board traces; reservations required a $199 deposit. Coinkite business development representative Celia Cherif said the Q1 was built mainly to help less advanced users.⁠[16][16][16][16][16][16][16][2][2]

That May, Coinkite launched the Edge firmware branch for the Mk4, aimed at developers and power users, with early support for new technologies such as Taproot and Miniscript and a warning not to use it for main holdings. In September, Donjon used double laser fault injection to read about half of the memory slots of the Mk4’s second secure chip, the DS28C36, but could not extract the master seed. Coinkite said the Mk4 stores the seed in the first secure chip, encrypted with a key that requires compromising both secure chips and the main processor, and that the research validated its multi-vendor secure chip design.⁠[17][17][17][17][17][18][7][18][18][18][18]

On April 17, 2025, Coinkite released the co-signing feature CCC (ColdCard Cosign) and Key Teleport. CCC lets a COLDCARD hold an additional key in a 2-of-3 multisig wallet that signs automatically under a spending policy with amount and velocity limits, an address whitelist and phone authentication codes; Key Teleport securely transfers seeds, passwords and multisig transactions between two COLDCARD Q devices by QR code or NFC, and can even clone an entire device to another person over a video call.⁠[19][19][19][19][19][19]

On September 29, 2025, Coinkite introduced spending policies for single-signer wallets, under which the device refuses to sign transactions that are too large, too frequent or sent to addresses outside a whitelist, with a separate dedicated PIN required to remove the policy. The same day, researcher Nathan Landon privately reported that its Delta PIN feature allowed full private-key recovery from two transaction signatures; Coinkite published a patch that day, and the fix shipped in firmware 5.4.4 and 1.3.4Q.⁠[20][20][20][7][7][7][7]

On March 10, 2026, Coinkite introduced the COLDCARD Mk5, with a 1.54-inch Gorilla Glass-protected display, a redesigned keypad, a more compact body with the USB-C port moved to the bottom, faster and more reliable NFC, and, for the first time, a choice of colors. Security features such as dual secure chips from two vendors, the genuine-firmware light at start-up and anti-phishing PIN prefix words were unchanged, and it is fully compatible with existing backups.⁠[21][21][21][21][21][21][21][21][21][21]

From May 1 to June 26, 2026, Coinkite reviewed its firmware with an enterprise AI tool, which produced 85 candidate findings, 8 of them high severity. After manually reviewing each one, it concluded that most high-severity items were false positives, intended behavior or documented trade-offs, but it also found and fixed a Delta Mode path that could expose a Seed Vault value through Seed XOR.⁠[7][7][7][7][7]

In June, some customers received paper letters impersonating Coinkite that urged them to upgrade firmware for “post-quantum” reasons. Coinkite warned that this was a scam to steal coins, said it would never send paper letters and that it deletes customer data, especially physical addresses, after 120 days, and judged that the senders’ data was mostly aggregated from leaks at other crypto companies; similar letters bearing competitors’ branding were also reported.⁠[22][22][22][22][22][22]

On July 30, 2026, Coinkite disclosed a seed-generation flaw in COLDCARD firmware that attackers had already used to steal funds. The problem stemmed from a build and link error during the March 2021 migration to the libNgU cryptographic library: the seed-generation path, which was meant to use only the hardware true random number generator, instead resolved to MicroPython’s built-in general-purpose pseudorandom number generator, Yasmarang. Affected were Mk2 and Mk3 firmware versions 4.0.1 through 4.1.9 and Mk4, Mk5 and Q firmware before their respective fixed versions; models from the Mk4 onward were less severely affected because entropy from two secure chips was mixed in, but their seeds had only about 72 bits of entropy instead of the expected 128.⁠[23][24][23][23][23][24][24][23][24]

Coinkite stressed that the devices themselves were not hacked or remotely controlled; attackers regenerated the private keys of weak seeds offline and stole funds. Updating the firmware secures only seeds generated afterward and cannot repair existing ones, so users had to generate new seeds and migrate their funds. Coinkite said it did not consider seeds at risk from this flaw alone if users had added at least 50 fair, independent and unexposed dice rolls when creating them; a strong, unique BIP-39 passphrase added an independent barrier, but those wallets should still be migrated as soon as practical. Fixed firmware for each model and release track began shipping on July 31.⁠[24][24][24][24][24][25][24]

In its technical write-up, Coinkite wrote that because COLDCARD’s source code had always been public, it had “to assume that someone used AI to review previous versions of our firmware and stumbled upon this issue,” and that a few weeks earlier it had used one of the best available AI models to review its code without finding the flaw. On August 4, the company said it had since tested frontier models including Kimi K3, Claude Fable and Codex 5.6, none of which caught it, and recommended that teams relying on AI review of security code test it specifically against build and submodule boundaries.⁠[23][23][26][26][26]

On August 2, Coinkite wrote that the previous three days had been some of the hardest in the company’s history. It had halted shipments once the vulnerability was confirmed and destroyed all inventory carrying the affected firmware, and it emailed customers whose orders had already shipped. It said its legal team would coordinate as warranted with law enforcement in multiple jurisdictions to identify those responsible, urged affected users not to dispose of their devices, and recommended other hardware wallets such as Bitkey, Ledger, Trezor, Jade and BitBox to users who needed a device quickly.⁠[27][27][27][28][27][27][27]

Galaxy DigitalGalaxy DigitalGalaxy Digital (Galaxy Digital Inc., Nasdaq and Toronto Stock Exchange: GLXY) is a New York-based digital asset financial services and data center infrastructure company founded by Mike Novogratz, which says it was founded in 2018. It provides institutional clients with digital asset trading, lending, investment banking, asset management, staking, and custody technology services, and is building data centers in Texas for artificial intelligence and high-performance computing.Open the full entry’s research arm counted in early August that three major attack waves and 14 smaller incidents had stolen 1,596 bitcoin from about 7,300 addresses, worth more than $100 million; a suspected fourth wave could bring losses to 2,055 bitcoin (about $130 million). Its head of research, Alex Thorn, said at least 15 different attackers had exploited the vulnerability. Blockchain analytics firm TRM Labs said the flaw cut key strength on some wallets from 128 bits to 40 bits, making them brute-forceable without physical access. On August 4 and 5, about 64 bitcoin and 200 ether were sent to the Wasabi and Tornado Cash mixing services respectively. The incident was also the main reason July became the second-worst month of 2026 for crypto thefts.⁠[29][29][29][30][31][31][31][31][31][32]

The incident prompted debate over how hardware wallets are tested. KrakenKrakenKraken is a digital-asset trading platform founded in 2011 by Jesse Powell and Thanh Luu and launched for trading in 2013. As Payward’s flagship brand, it has expanded into spot and derivatives trading, equities, tokenized assets, custody and payments through jurisdiction-specific entities.Open the full entry chief security officer Nick Percoco called it a “wake-up call” for hardware wallet makers and urged independent testing to verify that production firmware actually calls the approved randomness source; Dragonfly managing partner Haseeb Qureshi said about “$2 of AI hardening” could have prevented the attack, though an analyst noted that the claim that AI found the flaw in two minutes came from a scan made after the vulnerability was public, with no blind test. Swan CEO Cory Klippsten said clients were not abandoning self-custody but moving into multisig vaults.⁠[33][33][30][30][34][34][34]

On August 7, Coinkite announced that, because legal obligations arising from the incident required it to preserve records that might be relevant to legal proceedings, it had suspended its automatic deletion of customer data; customers who did not want their data preserved could ask to be exempted. That month it also published a page recording all known security research, coordinated disclosures and security advisories affecting COLDCARD.⁠[35][35][35][26]

On August 20, Coinkite released firmware 5.6.1 for the Mk4 and Mk5 and 1.5.1Q for the Q, describing it as the result of three more weeks of review after the July 31 hotfix, including AI-assisted review with Kimi and other frontier models. The new firmware requires every new seed to include user-supplied entropy — at least 65 unpredictably timed key presses, 50 dice rolls or 128 coin flips — mixed with entropy from both secure chips and the hardware random number generator; the backup pseudorandom generator was replaced with SHA-256 Hash_DRBG; and the device re-verifies a staged transaction immediately before signing, stopping if the host changed it after review. Coinkite also said law enforcement was still investigating the thefts.⁠[25][25][25][25][25][25][25][25]

In late August, Galaxy’s research arm attributed 1,789.28 bitcoin stolen from 8,865 addresses (worth about $114.7 million at the time of theft) to the case, of which 1,561 bitcoin (87.3%) had not moved, including everything taken in the first three attack waves; the median loss across 221 victim reports was about 1.04 bitcoin. From September 2, the third-wave attacker began swapping some bitcoin for ether through THORChain and sending funds into CoinJoin transactions, and by September 7 had moved about 45% of its haul. As of September 2026, the case was the third-largest crypto exploit of the year, behind the Kelp DAO and Drift thefts.⁠[36][36][36][36][36][37][37][37][37]

On September 21, Alex Thorn said white-hat hackers had moved 52.37 bitcoin they had swept from affected wallets for safekeeping into Wyoming-based Crypto Recovery Trust so it could be returned to victims, about 40% of the bitcoin associated with the second wave; victims can check on the trust’s website whether their funds are among them. Security researcher Nick Bax had said he helped rescue about 50 bitcoin at the end of July that was about to be stolen. Galaxy’s total at the time was 1,830 bitcoin across 9,162 addresses linked to the vulnerability.⁠[38][38][39][38][38]

On October 1, Coinkite released firmware 5.6.3 and 1.5.3Q, adding Codex32 backups based on BIP-93 with Shamir secret sharing, which can split the wallet on a device into two to nine shares with a user-chosen recovery threshold; as of October 2026, these are the standard firmware versions Coinkite recommends.⁠[40][40][40][41]

At about 02:00 UTC on October 11, 2026, a post disguised as an urgent security update appeared on COLDCARD’s official X account, @COLDCARDwallet, claiming that new firmware had a critical vulnerability affecting seed generation, telling users to migrate their wallets immediately, and linking to a website that used COLDCARD’s name. Community members quickly raised the alarm, and the post was deleted.⁠[42][42][43][43][43]

At 05:46 UTC, COLDCARD posted on the same account that it was investigating how a post containing a phishing link had been published from the account and that the post had been deleted. It warned users not to visit or interact with the link, stressed that its only official website is coldcard.com, and said the account had used offline two-factor authentication with tightly restricted access since 2017, that it had contacted X, and that it was reviewing all account access.⁠[44][44][44][44]

About 20 minutes later, COLDCARD publicly asked X Support for urgent escalation, saying a phishing post had appeared on its account yet it could find no corresponding login, session or access record and its credentials and offline two-factor authentication remained secure, which raised concern about unauthorized platform-level or administrative access. It also mentioned claims that access to X administrative accounts was being sold on darknet markets, while saying it could not independently verify a connection, and asked X to preserve all relevant logs and have its security team investigate immediately. Shortly after 14:00 UTC that day, it posted again that it was still waiting for X’s response. As of October 11, X had not publicly confirmed a platform breach, and there were no verified losses directly tied to the phishing post.⁠[45][45][45][45][45][46][46][47][43]

COLDCARD supports Bitcoin only, which Coinkite says keeps the code simpler, more auditable and with a smaller attack surface. The device can sign air-gapped via QR codes or MicroSD cards, keeping private keys offline; core setup requires no COLDCARD account or companion app, and it works with compatible coordinator software. The firmware source is published under MIT terms plus the Commons Clause with reproducible builds, so users can build it themselves and compare the result with the official release. The devices are designed and assembled in Canada.⁠[1][1][1][1][1][1][1]

As of October 2026, the models on sale are the full-featured COLDCARD Q (QWERTY keyboard, color screen, built-in QR scanner, NFC, MicroSD, USB-C and battery power) and the credit card-sized, pocketable Mk5, offering features such as Trick PINs, Seed XOR, BIP-85, temporary seeds and multisig. Coinkite’s other products include the physical bitcoin bearer tool Opendime, the NFC cards Tapsigner and Satscard, the Blockclock bitcoin data display and the stainless steel Seedplate seed backup; Opendime, Tapsigner and Satscard use different codebases and were not affected by the 2026 seed flaw.⁠[1][1][1][1][1][1][1][1][1][27]

COLDCARD: Official website: https://coldcard.com/ (opens in a new window).⁠[44][1]

Coinkite: Official website: https://coinkite.com/ (opens in a new window).⁠[1][48]

X: Public account: https://x.com/COLDCARDwallet (opens in a new window)⁠[5][1]