Ontology Mainnet Halt After Malicious Attack Activity

What happened

Ontology’s core development team paused mainnet block production on 31 August 2026 after what it first described as a potential security concern found during a routine check. A follow-up on 1 September confirmed it had identified malicious attack activity targeting the network. The chain resumed on 2 September, with every sync node required to upgrade to v3.1.5.

Ontology’s three announcements escalate in wording across the three days, from "a potential security concern" to "malicious attack activity targeting the network". All three say the activity did not involve or compromise user assets, and that ONT, ONG and other on-chain assets were unaffected. The v3.1.5 release on GitHub was published at 03:57 UTC on 2 September, which fits the stated resumption. No loss figure, no attack vector and no post-mortem have been published, so this is logged as a chain halt with an unpublished loss rather than a valued theft.