CVE-2026-33936

Basic Information

CVE State

PUBLISHED

Reserved Date

March 24, 2026

Published Date

March 27, 2026

Last Updated

April 01, 2026

Vendor

tlsfuzzer

Product

python-ecdsa

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.

CVSS Scores

SSVC Information

Exploitation

poc

Automatable

Yes

Technical Impact

partial

Exploit Status

Exploited in the Wild

Yes (2026-04-02 09:00:05 UTC) Source