Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The python-ecdsa package, versions before 0.19.2, mishandles truncated DER input: the helper function remove_octet_string() accepts data whose declared length exceeds the buffer, which can cause SigningKey.from_der() to raise an unexpected IndexError instead of a clean parsing error. An attacker who can supply a crafted DER private key to an application that parses it can cause a denial of service if the application does not catch unexpected exceptions. Upgrade to python-ecdsa 0.19.2 or later.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 5.3 | Medium | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0049, the 41st percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:11 UTC First seen by agentprime
- 31 Oct 2026, 14:11 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-9f5j-8jwj-x28g
- OSV: GHSA-9f5j-8jwj-x28g
- github.com/tlsfuzzer/python-ecdsa/security/advisories/GHSA-9f5j-8jwj-x28g
- nvd.nist.gov/vuln/detail/CVE-2026-33936
- github.com/tlsfuzzer/python-ecdsa/commit/bd66899550d7185939bf27b75713a2ac9325a9d3
- github.com/tlsfuzzer/python-ecdsa
- github.com/tlsfuzzer/python-ecdsa/releases/tag/python-ecdsa-0.19.2