GHSA-h9cc-w26m-j342 nimiq-keys: Denial of service in Ed25519 multisig delinearization via invalid curve points

• crates.io nimiq-keys: < 1.4.0 → fixed in 1.4.0

Impact A denial-of-service vulnerability exists in the Ed25519 multisig delinearization code path. `Ed25519PublicKey::delinearize()` in `keys/src/multisig/mod.rs` called `.unwrap()` on curve point decompression, which panics when a public key is constructed from 32 bytes that do not represent a valid point on the Ed25519 curve. `Ed25519PublicKey` construction only validates byte length, not curve membership, so invalid keys can reach the delinearization path and crash the hosting process. A secondary panic existed in `Commitment::From`, which similarly called `.unwrap()` on a failing curve point decompression. Who is affected: Browser and desktop wallet users of the web-client WASM library and the `nimiq-wallet` crate, when initiating a multisig operation with an attacker-supplied public key. An attacker must convince the user to include a crafted public key in a multisig setup — this is not a remotely triggerable node/validator crash. Who is NOT affected: Validator nodes, consensus, blockchain, mempool, and networking code. There is no on-chain multisig account type; multisig is a purely client-side construct, and no validator/consensus code calls the multisig delinearization path. Patches See PR. Workarounds No code-level workaround exists short of the patch. Users of wallet applications can mitigate exposure by only performing multisig operations with public keys received from trusted sources. Resources • Affected code: `keys/src/multisig/mod.rs`, `keys/src/multisig/commitment.rs`