The `ecdsa` PyPI package is a pure Python implementation of ECC (Elliptic Curve Cryptography) with support for ECDSA (Elliptic Curve Digital Signature Algorithm), EdDSA (Edwards-curve Digital Signature Algorithm) and ECDH (Elliptic Curve Diffie-Hellman). Prior to version 0.19.2, an issue in the low-level DER parsing functions can cause unexpected exceptions to be raised from the public API functions. `ecdsa.der.remove_octet_string()` accepts truncated DER where the encoded length exceeds the available buffer. For example, an OCTET STRING that declares a length of 4096 bytes but provides only 3 bytes is parsed successfully instead of being rejected. Because of that, a crafted DER input can cause `SigningKey.from_der()` to raise an internal exception (`IndexError: index out of bounds on dimension 1`) rather than cleanly rejecting malformed DER (e.g., raising `UnexpectedDER` or `ValueError`). Applications that parse untrusted DER private keys may crash if they do not handle unexpected exceptions, resulting in a denial of service. Version 0.19.2 patches the issue.
Project Subscriptions
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Advisories
| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-9f5j-8jwj-x28g | python-ecdsa: Denial of Service via improper DER length validation in crafted private keys |
Fixes
Solution
No solution given by the vendor.
Workaround
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References
History
Sat, 28 Mar 2026 03:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | The `ecdsa` PyPI package is a pure Python implementation of ECC (Elliptic Curve Cryptography) with support for ECDSA (Elliptic Curve Digital Signature Algorithm), EdDSA (Edwards-curve Digital Signature Algorithm) and ECDH (Elliptic Curve Diffie-Hellman). Prior to version 0.19.2, an issue in the low-level DER parsing functions can cause unexpected exceptions to be raised from the public API functions. `ecdsa.der.remove_octet_string()` accepts truncated DER where the encoded length exceeds the available buffer. For example, an OCTET STRING that declares a length of 4096 bytes but provides only 3 bytes is parsed successfully instead of being rejected. Because of that, a crafted DER input can cause `SigningKey.from_der()` to raise an internal exception (`IndexError: index out of bounds on dimension 1`) rather than cleanly rejecting malformed DER (e.g., raising `UnexpectedDER` or `ValueError`). Applications that parse untrusted DER private keys may crash if they do not handle unexpected exceptions, resulting in a denial of service. Version 0.19.2 patches the issue. | |
| Title | python-ecdsa: Denial of Service via improper DER length validation in crafted private keys | |
| Weaknesses | CWE-130 CWE-20 |
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| References |
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| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-03-27T22:08:22.868Z
Reserved: 2026-03-24T19:50:52.103Z
Link: CVE-2026-33936
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Status : Received
Published: 2026-03-27T23:17:13.733
Modified: 2026-03-27T23:17:13.733
Link: CVE-2026-33936
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OpenCVE Enrichment
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Github GHSA