Cosmos EVM Flaw Exploited After Cosmos Labs Knew Every Blockchain Running It Was Vulnerable
Attackers exploited a critical Cosmos EVM balance bug (GHSA-7g4w-cg88-2cq2) to drain funds from six blockchains; fixed in v0.6.2 and v0.7.2.
Cosmos Labs disclosed that a critical balance-handling flaw in the shared Cosmos EVM module (GHSA-7g4w-cg88-2cq2, no CVE) was exploited to drain funds from six blockchains between August 20 and 25, 2026. The bug, reported April 25 and initially judged harmless, lets vesting accounts delegate more than their spendable balance, wrapping balances to roughly 2^256 and triggering unintended mint/burn in reconciliation, potentially halting chains or burning victims' holdings. Fixes shipped in v0.6.2 and v0.7.2 on August 19 as state-breaking coordinated network upgrades; operators who cannot upgrade must halt their chains. The post-mortem notes the team used public silent patching for a fund-threatening issue, contrary to its own bug bounty policy, and that eleven deployments had never registered with its security channels.