CVE-2026-34061 nimiq CVE debrief

Who should care

Users of Nimiq Proof-of-Stake protocol, particularly those who manage validators, should be aware of this vulnerability and take steps to update to version 1.3.0 or later. They should also verify the integrity of block proposals and monitor for suspicious activity.

Technical summary

The vulnerability exists in the verify_macro_block_proposal() function, where an elected validator proposer can send an election macro block with a header.interlink that does not match the canonical next interlink. This can lead to the acceptance of a malicious block, which is later rejected during push with InvalidInterlink. The issue has been patched in version 1.3.0, and users are advised to update to this version or later.

Defensive priority

High

Recommended defensive actions

• Update to version 1.3.0 or later
• Verify the integrity of the block proposal
• Monitor for suspicious activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-04-03T23:17:03.940Z and last modified on 2026-07-24T22:10:00.140Z. The NVD entry is currently Analyzed. The vulnerability affects the Nimiq Proof-of-Stake protocol, specifically the verify_macro_block_proposal() function. Evidence of exploitation is limited, and defenders should verify the integrity of block proposals and monitor for suspicious activity.

Official resources