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Was Yoroi Hacked? The SecondFi Security Incident — What Happened and What to Do Now

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If you searched “yoroi hack”, you’re not alone. The short answer: Yoroi, EMURGO’s wallet, was rebranded as SecondFi in April 2026 and suffered a serious security incident between June 21 and 23, 2026. Here’s the breakdown — using primary sources and on-chain data — of what happened, how to tell if you’re affected, and what to do (and what not to do). Spoiler: as of July 30, there’s still no migration action to take.

Yoroi and SecondFi are the same wallet

  • In April 2026, EMURGO announced Yoroi was evolving into SecondFi, with automatic migration for all users (official announcement, cardano.org). That’s why the incident is called the “SecondFi hack”, although many people are still searching “yoroi hack”: it’s the same app.

What happened in June 2026: 16.1M stolen and ~130M secured

Between June 21 and 23, 2026, attackers drained ADA from addresses generated by the wallet software. Let’s separate two numbers that are often mixed up:

Figure What it means
~16.1M ADA Stolen by external attackers from 374 wallets, across 3 attacks. Sources: official statement and Fetch.
~129.43M ADA Preemptively secured/rescued by the team and white-hats from ~2,850 wallets on June 23; held in independent custody pending audit. Sources: Fetch and official statement.
  • Bitquery on-chain analysis: documents the movement of ~129 million ADA from 3,072 wallets to a vault wallet, and notes that it did not independently verify the rescue mechanics or custody. Source: Bitquery — an on-chain read, not a loss figure.

Why the confusion? Both movements happened on-chain in the same window and involved hundreds of millions of ADA; only one was an actual loss — the other was secured for return.

The root cause: Ed25519 implemented out of spec — not “nonce reuse”

The highest-quality technical analysis comes from Tibane Labs, verified against mainnet on-chain data. It corrects the press narrative:

  • This was not “nonce reuse” or “weak randomness.” It was an Ed25519 implementation that drifted from the spec: during key adaptation for the signer, the secret prefix kR was never wired in, so the nonce became r = SHA-512(M) — public and computable by anyone from the transaction body. It looks like nonce reuse, but it’s worse.
  • One signature was enough. With the nonce public, the private key falls out of the standard equation (a = (s−r)·H⁻¹). Any wallet that signed once with the affected build was exposed forever.
  • Verified on-chain, not speculation: Tibane recovered victims’ private keys from historical signatures and confirmed them by regenerating the public key (a·B == A). The detector (SHA-512(M)·B == R) produces no false positives and can enumerate exposed addresses.
  • Supply-chain (Tibane’s finding): the vulnerable build incorporated an experimental, unaudited SDK that, in the June rewrite (build 10.0.3), replaced EMURGO’s audited Rust library. This was a supply-chain governance failure, not a math failure.
  • Important: the Cardano protocol was not compromised; the network continued operating normally. Regarding attribution, an official SecondFi update from July 22, 2026 states that EMURGO commissioned Groom Lake for an independent forensic investigation. According to that assessment, the attack was sophisticated, external, and well-funded, with indicators consistent with a professional state-aligned actor and a possible overlap under evaluation with activity linked to Lazarus Group. No attribution has been confirmed.

Why restoring your seed phrase in another wallet doesn’t fix this

The risk isn’t in the seed phrase — it’s in the keys derived from the compromised address: exposure triggers at the moment of signing. Restoring your seed in another wallet doesn’t mitigate anything, and SecondFi does not recommend it (official statement and Tibane).

Who is exposed?

  • Rule of thumb: if you signed a transaction with the affected build starting June 8, 2026, treat that address as compromised. A single signature could have been enough.
  • Hardware wallets used as external signing devices are not affected by this bug.

SecondFi is shutting down: what about the funds?

  • On July 22, SecondFi announced it will not resume operations, per EMURGO’s official update on the Cardano forum.
  • EMURGO funded an on-chain recovery fund with ~16.1 million ADA plus tokens (July 1); distributions are pending external audit.
  • The ~129 million secured ADA remains in independent custody, and its return depends on final verification.

Am I affected? What to do now (and what not to)

Current status (July 30, 2026, official X account): the migration tool is NOT live. “There is no action to take yet.”

What to do

  1. Check your wallet using SecondFi’s official checker (it will never ask you to sign anything).
  2. If applicable, submit your ticket or claim through SecondFi’s official support.
  3. Keep your seed phrase safe and don’t delete the app.
  4. Wait for the official migration guide and tool (SecondFi has published a hardware wallet migration guide, but the tool is not yet live) and follow only official channels: X @secondfiapp and secondfi.io.

What NOT to do

  • Never share your seed phrase with anyone — including “support” that asks for it.
  • Don’t use third-party tools, extensions, or “recovery” services: anyone offering to migrate you before the official guide is a scam.
  • Don’t pay “fees” to recover funds, and don’t sign “test” transactions from affected addresses.

How to spot the active scams

Fake emails, websites, extensions, and apps impersonating SecondFi are circulating:

  • SecondFi will never ask for your seed phrase and will never contact you first.
  • The only official extension is on the Chrome Web Store with a blue check mark; official downloads only exist at secondfi.io/download.
  • The official checker never asks you to sign: any tool that requests a signature is fraud.
  • Note: yoroi-wallet.com is a stub with no phishing evidence; we’re not calling it out, but stick to official domains.

Alternatives to SecondFi on Cardano

  • If you’re evaluating alternatives, check our Cardano wallet guide. For significant amounts, a hardware wallet can add an extra layer of protection.

Sources and references

This article is educational and informational and does not constitute financial advice. Last updated: August 2, 2026; we’ll update it when EMURGO releases the official migration tool. Share it: the better informed the community is, the less room there is for scams.

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