A critical out-of-bounds error in the Nimiq core-rs-albatross protocol enables unauthenticated remote attackers to trigger a denial of service on validator nodes.

The vulnerability exists in the ProposalSender component due to an off-by-one error in the signer bounds check. This allows an unauthenticated remote peer to cause a panic via an out-of-bounds index, resulting in a process crash before signature verification occurs.

The successful exploitation of this vulnerability results in a denial of service for validator nodes, which directly disrupts the stability and availability of the Nimiq network. Given the CVSS score of 7.5, the high severity reflects the ability of remote, unauthenticated actors to degrade infrastructure reliability. This could lead to significant operational downtime for network participants and potential reputational damage for stakeholders relying on the consensus algorithm.

Immediate Action: Update the Nimiq core-rs-albatross implementation to version 1.3.0 or later to include the fix for the signer bounds check.

Proactive Monitoring: Monitor validator node logs for unexpected panic events or recurring process crashes that occur following the receipt of signed proposal messages.

Compensating Controls: While no direct WAF equivalent exists for this protocol-level flaw, ensure that validator nodes are isolated within restricted network segments to limit exposure to untrusted peers.

Public Exploit Available: No (exploit_available: false)

Operators of Nimiq validator nodes must prioritize the update to version 1.3.0 immediately. Because the vulnerability allows for remote, unauthenticated crashes of the consensus mechanism, failing to apply this patch exposes the infrastructure to trivial denial of service attacks that can halt local validation processes.