--- title: COLDCARD wallet RNG flaw likely linked to $88 million... description: A firmware flaw in COLDCARD hardware wallets caused the device to use a deterministic software random number generator (Yasmarang fallback) instead of the... canonical: https://daily.dev/posts/coldcard-wallet-rng-flaw-likely-linked-to-88-million-bitcoin-theft-oiit2xkec twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: COLDCARD wallet RNG flaw likely linked to $88 million Bitcoin theft | daily.dev og:description: A firmware flaw in COLDCARD hardware wallets caused the device to use a deterministic software random number generator (Yasmarang fallback) instead of the... og:url: https://daily.dev/posts/coldcard-wallet-rng-flaw-likely-linked-to-88-million-bitcoin-theft-oiit2xkec og:image: https://api.daily.dev/og/posts/Oiit2xkEc.png og:image:alt: COLDCARD wallet RNG flaw likely linked to $88 million Bitcoin theft og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # COLDCARD wallet RNG flaw likely linked to $88 million Bitcoin theft **[BleepingComputer](https://daily.dev/sources/bleepingcomputer)** · 4 min read · 6 upvotes · 1 comments ## Summary A firmware flaw in COLDCARD hardware wallets caused the device to use a deterministic software random number generator (Yasmarang fallback) instead of the STM32 hardware RNG. This allowed attackers to reconstruct wallet seeds offline, identify matching Bitcoin addresses on the blockchain, and drain funds. An estimated $88.6 million in Bitcoin was stolen from 4,585 addresses across multiple attack waves. Affected firmware spans Mk2/Mk3 versions 4.0.1–4.1.9 and various Mk4, Mk5, and Q versions before recent patches. Firmware updates are available but do not repair previously generated seeds — affected users must generate new seeds and migrate funds. Seeds supplemented with at least 50 dice rolls are not considered at risk from this flaw alone. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What caused the COLDCARD hardware wallet Bitcoin theft worth $88 million? An RNG integration error in COLDCARD firmware caused ngu.random to use MicroPython's deterministic Yasmarang fallback instead of the STM32 hardware random number generator. This made wallet seeds predictable because the fallback relied on the microcontroller identifier and system timing values, which are not cryptographically secure and may be reconstructable, letting attackers regenerate seeds offline and steal funds from over 4,500 addresses. _Track hardware wallet security disclosures like this one as they break on daily.dev._ ### Which COLDCARD firmware versions are affected by the RNG vulnerability and what should I do? Affected seeds were generated on Mk2/Mk3 firmware 4.0.1 through 4.1.9, Mk4/Mk5 before standard 5.6.0 or Edge 6.6.0X, and Q devices before standard 1.5.0Q or Edge 6.6.0QX. Updating to 4.2.0+, 5.6.0+, 1.5.0Q+, or 6.6.0X/6.6.0QX fixes the flaw going forward, but existing seeds must be regenerated and funds migrated since firmware updates don't repair a previously generated seed. _Bitcoin holders migrating wallets after a firmware flaw can follow updates like this on daily.dev._ ### Are COLDCARD seeds generated with dice rolls or a BIP-39 passphrase safe from this RNG flaw? Seeds supplemented with at least 50 fair, independent, and private dice rolls are not considered at risk from this flaw alone, according to Coinkite. A strong, unique BIP-39 passphrase also makes exploitation harder, but affected users should still migrate to a new seed since the passphrase does not repair the underlying compromised seed generation. _Crypto security practitioners weighing mitigation options can follow these disclosures on daily.dev._ ## Community discussion Top comments from developers on daily.dev. **@taiwofrancis** · 0 upvotes > A tough lesson for the crypto community. ## Similar posts on daily.dev - [They Didn’t Steal Your Keys. They Regenerated Them.](https://daily.dev/posts/they-didn-t-steal-your-keys-they-regenerated-them--zeogglmg2) · Coins Bench · 3 upvotes · 1 comments --- Tags: [#crypto](https://daily.dev/tags/crypto), [#vulnerability](https://daily.dev/tags/vulnerability) [View this post on daily.dev](https://daily.dev/posts/coldcard-wallet-rng-flaw-likely-linked-to-88-million-bitcoin-theft-oiit2xkec) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"COLDCARD wallet RNG flaw likely linked to $88 million Bitcoin theft","url":"https://daily.dev/posts/coldcard-wallet-rng-flaw-likely-linked-to-88-million-bitcoin-theft-oiit2xkec","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/coldcard-wallet-rng-flaw-likely-linked-to-88-million-bitcoin-theft-oiit2xkec"},"datePublished":"2026-08-02T21:17:43.782Z","dateModified":"2026-09-14T09:18:49.029Z","description":"A firmware flaw in COLDCARD hardware wallets caused the device to use a deterministic software random number generator (Yasmarang fallback) instead of the...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/2b24f7406df12d8d260b95c03efc7c95?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/2b24f7406df12d8d260b95c03efc7c95?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"BleepingComputer","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"BleepingComputer","logo":"https://media.daily.dev/image/upload/s--as8nJ3qy--/f_auto,q_auto/v1774959951/logos/bleepingcomputer?_a=BAMAMiWQ0","url":"https://daily.dev/sources/bleepingcomputer"},"commentCount":1,"discussionUrl":"https://daily.dev/posts/coldcard-wallet-rng-flaw-likely-linked-to-88-million-bitcoin-theft-oiit2xkec","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":6},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":1}],"keywords":"crypto,vulnerability","timeRequired":"PT4M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"BleepingComputer","item":"https://daily.dev/sources/bleepingcomputer"},{"@type":"ListItem","position":3,"name":"COLDCARD wallet RNG flaw likely linked to $88 million Bitcoin theft"}]} {"@context":"https://schema.org","@type":"WebPage","@id":"https://daily.dev/posts/coldcard-wallet-rng-flaw-likely-linked-to-88-million-bitcoin-theft-oiit2xkec","comment":[{"@type":"Comment","text":"A tough lesson for the crypto community.","datePublished":"2026-08-03T10:59:56.424Z","url":"https://daily.dev/posts/Oiit2xkEc#c-EPY8qthQ9","author":{"@type":"Person","name":"Francis","url":"https://daily.dev/taiwofrancis","image":"https://media.daily.dev/image/upload/s--Eux7Ia33--/f_auto,pg_1/v1792512435/avatars/avatar_FStpm3ZejUD3qGlEeoOUS?_a=BAMAMicg0"}}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/coldcard-wallet-rng-flaw-likely-linked-to-88-million-bitcoin-theft-oiit2xkec#faq","mainEntity":[{"@type":"Question","name":"What caused the COLDCARD hardware wallet Bitcoin theft worth $88 million?","acceptedAnswer":{"@type":"Answer","text":"An RNG integration error in COLDCARD firmware caused ngu.random to use MicroPython's deterministic Yasmarang fallback instead of the STM32 hardware random number generator. This made wallet seeds predictable because the fallback relied on the microcontroller identifier and system timing values, which are not cryptographically secure and may be reconstructable, letting attackers regenerate seeds offline and steal funds from over 4,500 addresses. Track hardware wallet security disclosures like this one as they break on daily.dev."}},{"@type":"Question","name":"Which COLDCARD firmware versions are affected by the RNG vulnerability and what should I do?","acceptedAnswer":{"@type":"Answer","text":"Affected seeds were generated on Mk2/Mk3 firmware 4.0.1 through 4.1.9, Mk4/Mk5 before standard 5.6.0 or Edge 6.6.0X, and Q devices before standard 1.5.0Q or Edge 6.6.0QX. Updating to 4.2.0+, 5.6.0+, 1.5.0Q+, or 6.6.0X/6.6.0QX fixes the flaw going forward, but existing seeds must be regenerated and funds migrated since firmware updates don't repair a previously generated seed. Bitcoin holders migrating wallets after a firmware flaw can follow updates like this on daily.dev."}},{"@type":"Question","name":"Are COLDCARD seeds generated with dice rolls or a BIP-39 passphrase safe from this RNG flaw?","acceptedAnswer":{"@type":"Answer","text":"Seeds supplemented with at least 50 fair, independent, and private dice rolls are not considered at risk from this flaw alone, according to Coinkite. A strong, unique BIP-39 passphrase also makes exploitation harder, but affected users should still migrate to a new seed since the passphrase does not repair the underlying compromised seed generation. Crypto security practitioners weighing mitigation options can follow these disclosures on daily.dev."}}]} ```