nimiq-blockchain is missing a wall-clock upper bound on block timestamps

### Impact 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. ### Patches TBD ### Workarounds No know workarounds.

Source published

10 Apr 2026 19:55:04 UTC

Source modified

10 Apr 2026 20:11:22 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Publisher rating · CRITICAL