In the Elliptic package 6.5.6 for Node.js ECDSA signature malleability occurs because BER-encoded signatures are allowed.

The npm package elliptic before version 6.5.4 are vulnerable to Cryptographic Issues via the secp256k1 implementation in elliptic/ec/key.js. There is no check to confirm that the public key point passed into the derive function actually exists on the secp256k1 curve. This results in the potential for the private key used in this implementation to be revealed after a number of ECDH operations are performed.

The Elliptic for Node.js allows ECDSA signature malleability via variations in encoding, leading '\0' bytes, or integer overflows. This could conceivably have a security-relevant impact if an application relied on a single canonical signature.