Significant Coldcard Losses as Fourth Attack Wave Targets 448 BTC

Coldcard Faces Significant Losses from Ongoing Attacks

On August 3, 2026, Galaxy Research head Alex Thorn reported a fourth coordinated attack wave targeting Coldcard wallets. This latest wave has seen approximately 448.7 BTC moved from 709 suspected victim addresses. The increased activity has raised alarms in the cryptocurrency community, especially given its scale.

Analysis of the Attack Patterns

Galaxy’s analysis indicated a striking rise in attack frequency, with 13.8 sweeps per block reported, a stark contrast to the 0.3 sweeps during pre-incident control periods. Initial assessments covered blocks from 960,778 to 960,792, identifying around 218 transactions linked to 462 possible victim addresses, equating to almost 388.9 BTC.

Vulnerable Seeds and Required Actions for Users

Following these findings, Thorn cautioned users to be particularly vigilant as similar transactions remain in Bitcoin’s mempool, awaiting confirmation. Users still managing affected keys may have the opportunity to issue conflicting transactions that could redirect their funds to safer wallets. However, once a transaction receives confirmation in a block, this option dissipates.

Understanding the Origin of Vulnerabilities

The wave of attacks has been traced back to an RNG integration error linked to a firmware update in March 2021. Coinkite, the manufacturer behind Coldcard, noted that this issue resulted in Mk2 and Mk3 seeds having diminished effective entropy, enhancing the potential for exploits. Although new firmware has been released to mitigate these vulnerabilities, users are still required to generate new seeds to ensure their funds’ safety.

Moving Forward: Emphasis on Security Measures

With thousands of addresses affected, the total lost across all waves now stands at an estimated 1,815.75 BTC from 5,294 addresses. Coinkite’s advisory highlights the necessity for a comprehensive migration to newly generated seeds to protect assets. Until confirmed through analysis by law enforcement or exchanges, the full scope of the losses remains uncertain.