Blockchain data infrastructure provider Allium has disclosed a security breach involving unauthorized access to parts of its systems, prompting service interruptions, API credential revocations and an independent cybersecurity investigation. The company detected the incident on October 25, 2026, and publicly confirmed the intrusion on October 28.
Chief executive and co-founder Ethan Chan said Allium immediately restricted unauthorized access, secured affected systems and notified customers believed to have been impacted. The company has engaged an external cybersecurity firm to investigate the incident and review its security controls.
Allium provides blockchain analytics and data infrastructure to financial and cryptocurrency businesses, including Visa, Stripe and Coinbase. However, the company has not identified which customers were directly affected, disclosed whether sensitive information was stolen or established how the attackers gained access.
Its primary application and Explorer APIs have resumed operations, although some services remain unavailable.
API Credentials Revoked as Core Services Recover
Allium’s public incident records show that its Explorer became unavailable on October 25, followed by a precautionary shutdown of its application on October 26. The company restored core Explorer functionality and associated APIs on October 28 after several days of disruption.
As part of its security response, Allium began revoking existing API keys and instructed customers to generate replacement credentials. Customers were also asked to set new passwords and encouraged to enable multifactor authentication. API keys authenticate software requests to data services, making credential replacement an important precaution when unauthorized access to infrastructure has been identified.
Allium temporarily disabled the ability to upload new datasets or access previously uploaded information. Queries relying on those customer-uploaded tables therefore remained unavailable. Its AI-powered Allium Assistant and Model Context Protocol service were also offline during the October 28 recovery update.
The company has not provided a definitive timetable for restoring those features. Importantly, the precautionary revocation of credentials does not independently establish that attackers obtained or misused every customer’s API keys.
The investigation remains ongoing, and Allium has promised to publish a summary of its findings and corrective measures.
Data Interruptions Highlight Institutional Infrastructure Risks
The incident also disrupted blockchain data delivery to customers using Snowflake, Databricks and Google BigQuery. An October 26 operational notice warned that some shared datasets were no longer receiving updated blockchain records. This created the possibility of stale information or incomplete query results for businesses relying on those feeds.
By October 28, Allium reported that data distribution had resumed across the three warehouse platforms. However, the company continued verifying data completeness and backfilling records missing from the disruption period. Datasets covering Ethereum, Bitcoin, Solana and Base were among those undergoing checks, while additional repairs continued for other networks and BigQuery records.
The distinction between restored connectivity and complete historical datasets matters for institutional users conducting transaction monitoring, financial analysis and blockchain research. Allium, founded in 2021, organizes raw blockchain transactions into structured datasets used by financial institutions and technology companies. Its partnership with Visa supports the payment network’s Onchain Analytics Dashboard, which analyzes stablecoin transaction activity.
The company also provides infrastructure to cryptocurrency businesses including Coinbase and has been associated with Stripe’s blockchain data operations. In June 2026, Allium raised $40 million in Series B financing led by Amplify Partners, with participation from Kleiner Perkins and Theory Ventures.
The company said its infrastructure supported data operations across more than 150 blockchains. The breach highlights the operational dependencies created as traditional financial institutions increasingly rely on specialized cryptocurrency infrastructure providers. Nevertheless, Allium’s disclosure does not establish that Visa, Stripe or Coinbase experienced unauthorized access to their own systems.
Nor has the company reported a confirmed loss of cryptocurrency or identified compromised customer funds. For affected businesses, immediate priorities include replacing credentials, reviewing account access and validating datasets covering the interruption.
The incident’s full significance will depend on the investigation’s findings concerning attacker access, potential data exposure and the effectiveness of Allium’s revised security controls.