Input validation error in python-ecdsa - CVE-2026-33936
Published: April 28, 2026
Vulnerability identifier: #VU128356
CSH Severity: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-33936
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
python-ecdsa
python-ecdsa
Software vendor:
Brian Warner
Brian Warner
Description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper input validation in SigningKey.from_der() when parsing untrusted DER private keys. A remote attacker can supply a specially crafted DER input to cause a denial of service.
The issue can trigger an internal IndexError instead of cleanly rejecting malformed DER.
Remediation
Install security update from vendor's website.