SecondFi, the self-custody finance platform built on Cardano, has entered maintenance mode after discovering a security vulnerability that affected a limited number of user wallets.
The platform announced on June 23 that it had identified and contained the issue before temporarily suspending front-end operations as investigations continue. The team said the move was taken to protect users while it works to determine the cause of the incident and restore services.
🚨 An Important Security Update from the SecondFi Team
We identified a security issue impacting a small number of Cardano wallets on our platform. We have contained the issue and paused the affected functions. Our engineering teams are actively working to restore full…
— SecondFi (@secondfiapp) June 23, 2026
How much was lost in the incident?
Community reports and on-chain data suggest the exploit resulted in the compromise of around 178 wallets, with estimated losses totalling roughly 12 million ADA, alongside various tokens and NFTs.
Blockchain activity linked to the incident reportedly showed nearly 200 suspicious transactions between June 21 and June 22, with funds moved through several addresses. While the figures have circulated within the Cardano community, SecondFi announced it has isolated the security incident to its native web wallet generation software, with on-chain analysis estimating the impact at around 16 million ADA.
The company said it is conducting an independent security review, has placed the platform in maintenance mode, taken balance snapshots, and is coordinating with Cardano leaders, including Input Output, the Cardano Foundation, and others, to protect the community.
What happens while SecondFi remains offline?
As part of the emergency response, SecondFi has disabled front-end access, preventing users from carrying out transactions and other wallet-related activities through the platform.
The team advised users to monitor wallet balances and transaction histories directly through Cardano blockchain explorers until services are restored. It also warned users about an increase in scam attempts following the incident.According to the company, official representatives will never request seed phrases, private keys, or fund transfers. Users seeking assistance have been urged to use only verified support channels.
Questions grow over the cause of the exploit
The security incident has sparked concern across the Cardano ecosystem, with users seeking clarity on what triggered the breach and which wallet versions may have been affected.
Community members have questioned whether the vulnerability was linked to mobile applications, browser extensions, transaction-signing processes, or another component of the platform’s infrastructure.
Meanwhile, SecondFi announced a partnership with Banxa to add fiat on-ramp and off-ramp services to its self-custody neofinance platform. The addition covers more than 180 markets and over 30 fiat currencies, giving users a simpler way to move between local money and digital assets.
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