What is CVE-2020-14039?

CVE-2020-14039 is a medium-severity vulnerability in Golang Go, classified under Improper Certificate Validation. CVSS score: 5.3/10. Published 2020-07-17.

How severe is CVE-2020-14039?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Is CVE-2020-14039 known to be exploited?

6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Golang Go

CVE-2020-14039

In Go before 1.13.13 and 1.14.x before 1.14.5, Certificate.Verify may lack a check on the VerifyOptions.KeyUsages EKU requirements (if VerifyOptions.Roots equals nil and the installation is on Windows). Thus, X.509 certificate verification is incomplete.

Vulnerability class: Improper Certificate Validation

Published 2020-07-17 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.018 (77.1th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 77th percentile — 77.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.018 · newest: 0.018 · change: 0.000

Affected products

Golang Go
openSUSE Leap — versions 15.1, 15.2

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

Public proof-of-concept exploits

References

groups.google.com/forum/
lists.opensuse.org/opensuse-security-announce/2020-07/msg00077.html (vendor-advisory, Mailing List, Third Party Advisory)
lists.opensuse.org/opensuse-security-announce/2020-07/msg00082.html (vendor-advisory, Mailing List, Third Party Advisory)
lists.opensuse.org/opensuse-security-announce/2020-09/msg00029.html (vendor-advisory, Mailing List, Third Party Advisory)
lists.opensuse.org/opensuse-security-announce/2020-09/msg00030.html (vendor-advisory, Mailing List, Third Party Advisory)
www.oracle.com/security-alerts/cpuApr2021.html (Patch, Third Party Advisory)
groups.google.com/forum/
security.netapp.com/advisory/ntap-20200731-0005/ (Third Party Advisory)

Frequently asked questions

What is CVE-2020-14039?: CVE-2020-14039 is a medium-severity vulnerability in Golang Go, classified under Improper Certificate Validation. CVSS score: 5.3/10. Published 2020-07-17.
How severe is CVE-2020-14039?: Medium severity. CVSS v3 base score is 5.3 out of 10.
Is CVE-2020-14039 known to be exploited?: 6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.