A flaw was found in all python-ecdsa versions before 0.13.3, where it did not correctly verify whether signatures used DER encoding. Without this verification, a malformed signature could be accepted, making the signature malleable. Without proper verification, an attacker could use a malleable signature to create false transactions.
References
- https://nvd.nist.gov/vuln/detail/CVE-2019-14859
- https://github.com/warner/python-ecdsa/issues/114
- https://github.com/warner/python-ecdsa/pull/115
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-14859
- https://github.com/warner/python-ecdsa/releases/tag/python-ecdsa-0.13.3
- https://pypi.org/project/ecdsa/0.13.3/
- https://github.com/advisories/GHSA-8qxj-f9rh-9fg2