The flaw stems from missing validation that a header’s body_root matches the hash of the actual macro body. Prior to v1.2.2, a malicious or compromised validator elected as proposer could submit a proposal with a mismatched body_root. The proposal passes initial checks, but downstream code expects the binding and may panic on the mismatch, causing the validator to crash. This results in denial‑of‑service for the impacted node while leaving the network functional but with a reduced set of healthy validators.

The vulnerability affects the nimiq core-rs-albatross implementation of the Nimiq Proof‑of‑Stake blockchain. All validator nodes running versions older than 1.2.2 are susceptible. The fix is included in release v1.2.2.

The CVSS score is 7.1, indicating a high severity. The EPSS score is less than 1 %, so exploitation is considered unlikely at present. The vulnerability is not listed in CISA’s KEV catalog. An attacker must control a validator and be elected as proposer to exploit it; thus the attack vector is internal validator election, and the impact is limited to the compromised node. A crash of the validator can disrupt the consensus process if the node holds a significant stake, but the network can tolerate a few nodes going offline. As no public workaround exists, the recommendation is to apply the patch.