CVE-2026-40093: Nimiq Proof-Of-Stake

High severity, CVSS 8.1. EPSS: 0.4% chance of exploitation in the next 30 days.

nimiq-blockchain provides persistent block storage for Nimiq's Rust implementation. In 1.3.0 and earlier, block timestamp validation enforces that timestamp >= parent.timestamp for non-skip blocks and timestamp == parent.timestamp + MIN_PRODUCER_TIMEOUT for skip blocks, but there is no visible upper bound check against the wall clock. A malicious block-producing validator can set block timestamps arbitrarily far in the future. This directly affects reward calculations via Policy::supply_at() and batch_delay() in blockchain/src/reward.rs, inflating the monetary supply beyond the intended emission schedule.

Affected products

• Nimiq Nimiq Proof-Of-Stake: before 1.3.0 (fixed in 1.3.0)

Published 2026-04-09. Last modified 2026-06-17.