What is CVE-2019-20399?

CVE-2019-20399 is a medium-severity vulnerability in Parity Libsecp256k1, classified under Observable Discrepancy. CVSS score: 5.9/10. Published 2020-01-23.

How severe is CVE-2019-20399?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Parity Libsecp256k1

CVE-2019-20399

A timing vulnerability in the Scalar::check_overflow function in Parity libsecp256k1-rs before 0.3.1 potentially allows an attacker to leak information via a side-channel attack.

Published 2020-01-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.009 (57.5th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 57.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Parity Libsecp256k1

Weakness classification (CWE)

CWE-203 — Observable Discrepancy

References

github.com/paritytech/libsecp256k1/commit/11ba23a9766a5079918cd9f515bc100bc8164… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2019-20399?: CVE-2019-20399 is a medium-severity vulnerability in Parity Libsecp256k1, classified under Observable Discrepancy. CVSS score: 5.9/10. Published 2020-01-23.
How severe is CVE-2019-20399?: Medium severity. CVSS v3 base score is 5.9 out of 10.