Elliptic Cryptanalysis vulnerability when `k` has leading zeros

Vulnerability Description

The ECDSA implementation of the Elliptic package generates incorrect signatures if an interim value of 'k' (as computed based on step 3.2 of RFC 6979 https://datatracker.ietf.org/doc/html/rfc6979 ) has leading zeros and is susceptible to cryptanalysis, which can lead to secret key exposure. This happens, because the byte-length of 'k' is incorrectly computed, resulting in its getting truncated during the computation. Legitimate transactions or communications will be broken as a result. Furthermore, due to the nature of the fault, attackers could–under certain conditions–derive the secret key, if they could get their hands on both a faulty signature generated by a vulnerable version of Elliptic and a correct signature for the same inputs. This issue affects all known versions of Elliptic (at the time of writing, versions less than or equal to 6.6.1).

References

• https://www.herodevs.com/vulnerability-directory/cve-2025-14505
• https://github.com/indutny/elliptic/issues/321