The flaw resides in the Ed25519 multisig delinearization routine of the Rust-based Nimiq core. The routine unconditionally unwraps a decompression result from an Ed25519 public key, meaning that a call with 32 bytes that do not map to a valid curve point will panic. This panic kills the entire service process, resulting in a denial of service that affects the availability of the node. The vulnerability does not compromise confidentiality or integrity; it simply aborts the node when a malformed key is processed.

The affected product is the Nimiq core implementation called core‑rs‑albatross. Any build prior to version 1.4.0 – for example 1.3.x, 1.2.x, and older releases – contains the unprotected .unwrap() call. Nodes running those older versions can be compromised when they accept multisignature inputs that include a public key derived from an arbitrary 32‑byte blob.

The CVSS score of 4.3 indicates moderate severity because the exploit requires an attacker to supply a crafted public key that reaches the delinearization path. The EPSS score is not published, and the vulnerability is not listed in the CISA KEV catalog. The likely attack vector is external: a remote participant could submit a malicious multisig transaction or message that includes an invalid Ed25519 point, trigger the crash, and cause a denial of service. If a node does not perform additional sanity checks on multisig keys, the execution path of the crash is straightforward, making exploitation practical but still limited to nodes that expose the vulnerable code.