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.
bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-14859
github.com/tlsfuzzer/python-ecdsa/commit/3427fa29f319b27898a28601955807abb44c0830
github.com/tlsfuzzer/python-ecdsa/commit/9080d1d5ac533da0de00466aaffb49bee808bb4e
github.com/tlsfuzzer/python-ecdsa/commit/b0ea52bb3aa9a16c9a4a91fdc0041edbfed10b31
github.com/warner/python-ecdsa
github.com/warner/python-ecdsa/issues/114
github.com/warner/python-ecdsa/pull/115
github.com/warner/python-ecdsa/releases/tag/python-ecdsa-0.13.3
nvd.nist.gov/vuln/detail/CVE-2019-14859
pypi.org/project/ecdsa/0.13.3