Security advisories 2026
Four 2026 incidents that matter directly to anyone storing a seed phrase: a seed-generation flaw in COLDCARD firmware, a shipping-provider breach that exposed Trezor customers' names and addresses, a phishing email sent through Trezor's newsletter provider, and Ledger devices fitted with a hidden implant before sale. For each one, Seed Phrase Field Guide sets out what happened, who is affected and what the maker says to do, with links to the maker's own statement.
Advisories change quickly. If we get a detail wrong, the fix is recorded in the corrections log; device terms are defined in the glossary.
Key takeaways
- COLDCARD (disclosed 30 July 2026): seeds generated on affected firmware may be weak. Install fixed firmware, generate a new seed and move funds, with a test transaction first (COLDCARD).
- Trezor via ShipMonk (13 August 2026, updated 4 September): names, emails, phone numbers and shipping addresses of some customers were exposed. No wallet data was involved, but expect convincing phishing and letters (Trezor shipping data).
- Trezor via Brevo (9–10 September 2026): a phishing email went to newsletter subscribers. Only people who typed their wallet backup into the phishing app lost control of it (Trezor).
- Ledger via CryptoBilis (9–15 October 2026): do not set up an unused device bought from that reseller; if one is already set up, move funds to a new device with a new recovery phrase (Ledger).
- No genuine advisory from any maker asks you to type your seed words into a website, app, email reply or form (a short routine).
Summarised from this page only. Follow each link for the detail and the sources behind it. Educational information, not advice.
At a glance Beginner
| Incident | Disclosed | Who is affected | What to do (in short) |
|---|---|---|---|
| COLDCARD weak seed generation | 30 July 2026 (updated 1 and 30 August; status page updated 1 October) | Seeds generated on affected COLDCARD firmware (Mk2, Mk3, Mk4, Mk5 and Q), unless the dice exception applies | Install fixed firmware, generate a new seed, move funds with a test transaction first |
| Trezor customer data exposed at shipping provider ShipMonk | 13 August 2026 (updated 14 August and 4 September) | Trezor customers emailed by Trezor about the breach: some recent orders to the US, UK, Sweden, Colombia, Brazil, Italy and Portugal, plus about 67,000 older US orders | Treat unexpected emails, calls and letters as phishing; never give your wallet backup to anyone |
| Trezor newsletter phishing via Brevo | 9–10 September 2026 (updated 17 September) | People on Trezor's newsletter list; only those who typed their wallet backup into the phishing app lost control of it | Ignore and delete the email; if you entered your backup anywhere, move funds to a new wallet now |
| Ledger devices with an implant sold through CryptoBilis | 9–15 October 2026 | People who bought a Ledger device through the reseller CryptoBilis (Southeast Asia) | Do not set up an unused device; if already set up, move funds to a new device with a new recovery phrase |
COLDCARD: weak seed generation in affected firmware Intermediate
Evidence: what went wrong and what to do: Grade 2 Primary documentation (Coinkite's advisory and backgrounder about its own firmware). The root cause: Grade 1 Independent test (Block Engineering's published analysis). Loss totals are third-party estimates, not test results.
What happened
Coinkite, which makes COLDCARD, published a security advisory on 30 July 2026 and updated it on 1 August and 30 August 2026. It says a firmware bug in affected releases weakened seed generation. The devices themselves were not hacked or remotely accessed: attackers rebuilt the weak seeds offline, recreated the private keys and moved the funds. Independent analyses by Block's engineering team and Coinkite's own technical backgrounder trace this to a build-configuration error that sent seed generation to a non-cryptographic software generator instead of the hardware random source (Coinkite advisory · Coinkite technical backgrounder · Block Engineering analysis).
Who is affected
| Model | Seeds generated on | Fixed firmware (standard track) | Fixed firmware (Edge track) |
|---|---|---|---|
| Mk2 and Mk3 | Firmware 4.0.1 (March 2021) to 4.1.9 inclusive; the more severe case | 4.2.0 or later | n/a |
| Mk4 and Mk5 | Any firmware before the fixed release; about 72 bits of entropy instead of 128, per Coinkite | 5.6.0 or later | 6.6.0X or later |
| Q | Any firmware before the fixed release; about 72 bits instead of 128, per Coinkite | 1.5.0Q or later | 6.6.0QX or later |
Coinkite says standard and Edge are separate release tracks, so an older Edge 6.x release is not fixed just because its number is higher. It also says TAPSIGNER, OPENDIME and SATSCARD are not affected, as they use different code. Updating the firmware does not repair a seed that was already generated: it only fixes new seeds.
What has changed since the fix?
The minimum fixed releases in the table above are unchanged on Coinkite's Security Status page, which it describes as the living record of the incident (page updated 1 October 2026; Coinkite says a separate, detailed technical postmortem is still in preparation). Since the 31 July fix Coinkite has published three more releases for Mk4, Mk5 and Q:
- 5.6.1 and 1.5.1Q (20 August 2026): a security release from a wider review. Every newly generated seed now needs one input from you as well as the device's own randomness: at least 65 key presses with unpredictable timing, 50 rolls of a physical die or 128 coin flips. The backup software generator was also replaced (Coinkite, 20 August).
- 5.6.2 and 1.5.2Q (4 September 2026), with Edge 6.6.1X and 6.6.1QX: shows the device-generated input as words before your own input is mixed in, and adds a tool for checking the mixing on an offline computer. Coinkite says to treat every applicable COLDCARD release as a critical update "for the next while" (Coinkite, 4 September).
- 5.6.3 and 1.5.3Q (1 October 2026): Coinkite's current recommended standard releases. They keep the seed-generation fixes and add features, including Codex32 (Shamir) backups (Coinkite, 1 October).
Coinkite also says that Mk2/Mk3 firmware 4.2.0 is the final release for those models. It can still generate a correct replacement seed, but Coinkite recommends moving long-term storage to a current model. It describes the independent checks of the fix as targeted reviews, not a complete audit of every firmware file. None of these releases repairs a seed that was already generated on affected firmware, and the migration advice is unchanged (Coinkite migration guide).
The two exceptions: dice rolls and passphrases
- Dice rolls. On affected firmware the device mixed the dice rolls you entered (Add Dice Rolls) into the seed. Coinkite says that if you entered at least 50 fair, independent, private rolls that were never recorded or exposed, it does not consider the resulting seed at risk from this bug alone (50 to 98 rolls give at least 128 bits; 99 or more about 256 bits). If you rolled fewer than 50, cannot remember, or are unsure which words you used, Coinkite says to migrate.
- BIP39 passphrase. A strong, unique BIP39 passphrase (not the COLDCARD PIN) is an extra barrier: the weak seed alone does not reach a passphrase wallet. But Coinkite says it does not repair the seed, a short, common or reused passphrase may be guessable, and passphrase users should still migrate "as soon as practical". See passphrase pitfalls.
What to do if you are affected
This summarises Coinkite's migration steps. Read the advisory itself before you start, because it also covers using a single Mk2/Mk3 for both the old and new wallets.
- Do not create a new seed on an affected model until the fixed firmware is installed, and check the version on the device itself.
- Generate a new seed on the updated COLDCARD (Coinkite's advisory says dice are optional for fixing this issue; from 5.6.1 and 1.5.1Q the device asks for one input from you, such as key presses or dice, for every new seed), and write down and verify the backup before sending anything to it.
- Check a receive address for the new wallet on the COLDCARD screen.
- Send a small test amount and confirm it arrives.
- Only then move the rest of the funds. Keep the old backup until the whole balance has arrived and is confirmed.
Coinkite warns that rushing a migration can be riskier than the issue itself. If the seed is part of a multisig wallet, replace that key and create a new wallet configuration (see multisig recovery).
Losses (third-party estimates, preliminary)
Coinkite's advisory gives no loss total. Galaxy Research, which tracked the thefts on-chain and spoke to victims, said on 14 August 2026 that it had high confidence that 1,778.84 BTC had been stolen from more than 8,600 addresses, and that the total could reach 2,417.35 BTC if unconfirmed activity is included (Galaxy Research). CoinDesk reported on 17 August 2026 how the bug went unnoticed in public code for years (CoinDesk). These are third-party estimates, not confirmed by Coinkite, and may change.
Primary sources: Coinkite: COLDCARD security advisory (30 July 2026, updated 1 and 30 August 2026) · COLDCARD Security Status (updated 1 October 2026). More on this site: randomness case note · case file · mixing your own dice into a seed.
Trezor: customer data exposed at its shipping provider, ShipMonk Beginner
Evidence: Grade 2 Primary documentation (Trezor's statement about its own customers). We have not seen a statement from ShipMonk.
What happened
Trezor says that on 10 August 2026 ShipMonk, one of its shipping providers, told it about unauthorised access to ShipMonk's systems. Trezor's first figures were 11,742 customers with full exposure (name, email, phone number and shipping address) and 1,947 with partial exposure (name, city and email), for orders delivered to the US, UK, Sweden, Colombia, Brazil, Italy and Portugal between 10 May and 8 August 2026. In its 4 September update Trezor said ShipMonk had told it on 2 September that the breach also held order data from November 2019 to August 2021, affecting about 67,000 more US customers with full exposure, even though Trezor had received written confirmation that this data had been deleted. Trezor says its own systems and devices were not affected, and that affected customers were emailed directly (Trezor statement).
What to do
- No seed, PIN or wallet data was involved. Your coins are only at risk if you are tricked into revealing your wallet backup.
- Expect targeted phishing: emails, calls and printed letters that use your real name, address and order details, possibly pretending to be Trezor, a bank or an exchange. Trezor shows examples of fake letters and warns of possible physical security risks. See social engineering after customer data leaks and physical threats.
- Trezor says that if you did not receive its email about the breach, you are not affected. Check that any such email is genuine before acting on it, and never use a link in it to enter anything.
Primary source: Trezor: recent customer data exposed in shipping provider incident (13 August 2026, updated 4 September). More on this site: printed scam letters (2025 case).
Trezor: phishing email sent through its newsletter provider, Brevo Beginner
Evidence: Grade 2 Primary documentation (Trezor's statement and Brevo's incident write-up, each about its own systems). Reporting by BleepingComputer and SecurityWeek is named where used.
What happened
Trezor says that on 9 September 2026 Brevo, the third-party marketing platform it uses for newsletters, suffered a security incident, and an attacker used Trezor's Brevo account to email its opt-in newsletter list. The subject line was "Critical Security Alert: STM32 Entropy Vulnerability". The email linked to an app that asked people to enter their wallet backup. Trezor says it took the domain down at DNS level within 20 minutes, by which time about 2,500 people had clicked the link, and that no Trezor product, wallet or other system was affected (Trezor statement).
Brevo's own write-up says it found the problem on 10 September 2026 at 06:30 UTC: an attacker exploited a flaw in how Brevo handled SAML single sign-on to get into 138 Brevo accounts, sent phishing from 6 of them and exported contacts from 43. Brevo says the messages went through legitimate infrastructure, so they passed the usual email authentication checks and looked genuine (Brevo incident write-up). Trezor's post gives a different count of affected Brevo accounts (120); we report both as stated. BleepingComputer reported that recipients saw the email come from a genuine Trezor address (BleepingComputer, 10 September).
Who is affected
- People on Trezor's newsletter list. In an update on 17 September 2026, Trezor said Brevo had confirmed that 347,149 marketing email contacts were exported, so those addresses may get more targeted phishing in future.
- Trezor says that only people who entered their wallet backup into the app, or anywhere online, are at risk. Clicking the link alone does not expose funds, and Brevo held no passwords or wallet data.
- SecurityWeek reported that BitBox and CoinTracking also appeared to have been hit through Brevo, but that neither had named Brevo or shared details (SecurityWeek, 11 September). We have not verified that ourselves.
What to do
- Do not click links in any email claiming to be from a wallet maker about a "vulnerability". Delete it. Go to the maker's site by typing the address or using your own bookmark.
- If you entered your wallet backup into the app, a website or any form, treat the seed as exposed: Trezor says to move your funds to a new wallet immediately. See if you think your seed was exposed.
- If you only clicked, or did nothing, Trezor says your assets remain secure. Expect more phishing to that email address.
Primary sources: Trezor: security incident at Brevo (10 September 2026, updated 17 September) · Brevo: incident write-up. Reporting: BleepingComputer (10 September) · BleepingComputer (347,000 users) · SecurityWeek (11 September). More on this site: case file · a quick check before you act on any message.
Ledger: devices with a hidden implant sold through CryptoBilis Intermediate
Evidence: Grade 2 Primary documentation (Ledger's own statements, as published and as reported). The device model named by researchers and the reported retail sales pause are Grade 5 Unverified: we could not confirm them from Ledger.
What happened
- 9 October 2026: Ledger said it was investigating reports of drained wallets and asked CryptoBilis, a Malaysia-based reseller selling across Southeast Asia, to stop selling and shipping Ledger devices (BleepingComputer).
- 10–11 October: Ledger confirmed that one affected user's device contained an unauthorised hardware implant, and said that all confirmed cases tied to the 9 October draining involved devices sold through CryptoBilis, describing the volume as limited (CoinDesk, 12 October).
- 13 October: in an update from its security lab, the Ledger Donjon, Ledger said the implant sits inside the case and reads what is shown on the screen. During setup, when the device displays the 24-word recovery phrase, the implant decodes the words and sends them out over a mobile (LTE) connection using an eSIM. Ledger said it does not change the Secure Element, the operating system, transactions or signatures, and that it had not confirmed the total number of affected users or the value lost (CoinDesk, 13 October).
- 15 October: Ledger's blog said an organised criminal group had bought genuine devices, opened them, fitted hidden components and put them back into distribution through resellers in Southeast Asia. Ledger said there was no flaw in its chip, operating system or servers, that its own checks of stock and of devices bought in shops (including in Germany) found no compromised units, and that it had asked its authorised resellers and distributors to suspend sales in Southeast Asia and Hong Kong. Ledger called it "a localized distribution attack", not a systemic supply-chain attack. It also set new rules for its authorised resellers with immediate effect: returned devices must never be resold, devices must no longer go on shelves or displays and should be handed over at the time of purchase, and customer reports of an unusual product must be passed to Ledger promptly. Ledger said it would publish more details later (Ledger statement).
Who is affected
People who bought a Ledger device through CryptoBilis. Ledger said it had not verified a theft involving a device bought elsewhere, but was reviewing reports of implants in other devices and places (CoinDesk, 13 October). Ledger has not named the model. Researchers quoted by BleepingComputer described implants inside Ledger Nano X units bought from marketplace sellers shipping from Malaysia; that detail comes from those researchers, not from Ledger. The Hacker News reported a write-up by Tibane Labs describing three versions of the implant, one in a device bought on Amazon Japan from a third-party seller and shipped from Malaysia (The Hacker News). Ledger has not confirmed this Grade 5 Unverified.
BleepingComputer also reported that Ledger warns its "Genuine Check" cannot detect added components while the original Secure Element is intact. In other words, a device can pass the authenticity check and still have been tampered with.
What to do (Ledger's advice, as reported 13 October)
- If you bought a Ledger device from CryptoBilis and have not set it up, do not set it up, and contact Ledger Support.
- If you have set it up, move your assets promptly to a new device with a new recovery phrase, generated on that new device.
- Do not enter or restore any recovery phrase on a device bought from CryptoBilis.
- If you lost funds or hold a tampered device, contact Ledger Support through support.ledger.com and report it to your local police. Ledger says not to send the device to anyone, or open it, before speaking to Ledger Support or the police.
For any new hardware wallet, buy from the maker's own shop or a reseller on the maker's official list, and never use a device that arrives already set up or with a recovery phrase. See supply-chain checks for a new device.
What we left out
We have not published loss totals: Ledger says figures circulating online come from third parties and that it has not verified them. CoinDesk reported that Ledger said MediaMarkt Saturn had stopped selling its devices after a report from one customer in Germany. We could not find that in a Ledger statement we could load, so we mention it only as reported. Ledger says its own checks of devices bought in German shops found none compromised.
Primary source: Ledger: response to the hardware implant attack (15 October 2026). Reporting: BleepingComputer (12 October) · CoinDesk (12 October) · CoinDesk (13 October) · The Hacker News (Tibane Labs report). More on this site: case file · hardware wallet advisories table.
What should you do when any advisory appears? Beginner
- Check that it is real. Find the advisory on the maker's own website or official account, reached by your own bookmark, not through a link in an email or message.
- Check whether it applies to you. Note your model, the firmware version that created your seed, where you bought the device and whether you used dice or a passphrase. Keeping this in your records makes it easy.
- Follow the maker's steps, slowly. If they say to generate a new seed, do it on a fixed or new device, verify the backup, then do a test transaction before moving everything.
- Never enter a seed anywhere to "check" it. No legitimate checker needs your recovery phrase.
Older device findings are in the advisories table; past weak-randomness cases are on the randomness page; phishing and supply-chain cases are in the case files.
Educational information only, not legal, financial or security advice. Checked and re-checked 25 October 2026. Seed Phrase Field Guide has no commercial relationship with any maker named here.
Last reviewed: · Educational information only — verify current details with official sources.