Improper Verification of Cryptographic Signature in Pure-Python ECDSA
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | ecdsa | < 0.13.3 | 0.13.3 |
References
- 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://github.com/warner/python-ecdsa/issues/114
- https://pypi.org/project/ecdsa/0.13.3/
- https://github.com/advisories/GHSA-8qxj-f9rh-9fg2
- https://nvd.nist.gov/vuln/detail/CVE-2019-14859
- https://github.com/warner/python-ecdsa/pull/115
- https://github.com/tlsfuzzer/python-ecdsa/commit/3427fa29f319b27898a28601955807abb44c0830
- https://github.com/tlsfuzzer/python-ecdsa/commit/9080d1d5ac533da0de00466aaffb49bee808bb4e
- https://github.com/tlsfuzzer/python-ecdsa/commit/b0ea52bb3aa9a16c9a4a91fdc0041edbfed10b31
- https://github.com/pypa/advisory-database/tree/main/vulns/ecdsa/PYSEC-2020-163.yaml
- https://github.com/warner/python-ecdsa
- https://pypi.org/project/ecdsa/0.13.3
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N- Weakness (CWE)
CWE-347- Platform
- Python (PyPI)
- Package
ecdsa- Disclosed
- 02.01.2020
- Updated
- 11.10.2026 12:19
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2020-163 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-8qxj-f9rh-9fg2 - CC BY 4.0
Vulnerability history: ecdsa
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 01.2020 03.2026
- Without a fix
- 1
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 1
- Medium 1
Disclosures per year
- 2020: 1
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 1
- 2025: 0
- 2026: 1
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Improper Verification of Cryptographic Signature in Pure-Python ECDSA this entry
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