{"id":"CVE-2026-33936","summary":"python-ecdsa: Denial of Service via improper DER length validation in crafted private keys","details":"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.","aliases":["GHSA-9f5j-8jwj-x28g"],"modified":"2026-04-18T08:14:11.779747759Z","published":"2026-03-27T22:08:22.868Z","related":["CGA-g392-rr6w-3vvm","SUSE-SU-2026:1436-1","openSUSE-SU-2026:10468-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33936.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-130","CWE-20"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33936.json"},{"type":"FIX","url":"https://github.com/tlsfuzzer/python-ecdsa/commit/bd66899550d7185939bf27b75713a2ac9325a9d3"},{"type":"WEB","url":"https://github.com/tlsfuzzer/python-ecdsa/releases/tag/python-ecdsa-0.19.2"},{"type":"ADVISORY","url":"https://github.com/tlsfuzzer/python-ecdsa/security/advisories/GHSA-9f5j-8jwj-x28g"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33936"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/tlsfuzzer/python-ecdsa","events":[{"introduced":"0"},{"fixed":"bd66899550d7185939bf27b75713a2ac9325a9d3"}],"database_specific":{"versions":[{"introduced":"0"},{"fixed":"0.19.2"}]}}],"versions":["python-ecdsa-0.10","python-ecdsa-0.11","python-ecdsa-0.12","python-ecdsa-0.13","python-ecdsa-0.14","python-ecdsa-0.14.1","python-ecdsa-0.15","python-ecdsa-0.16.0","python-ecdsa-0.16.1","python-ecdsa-0.17.0","python-ecdsa-0.18.0","python-ecdsa-0.18.0b1","python-ecdsa-0.18.0b2","python-ecdsa-0.19.0","python-ecdsa-0.19.1","python-ecdsa-0.5","python-ecdsa-0.6","python-ecdsa-0.7","python-ecdsa-0.8","python-ecdsa-0.9"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33936.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}