What is CVE-2020-8156?

CVE-2020-8156 is a high-severity vulnerability in Nextcloud Mail, classified under Improper Certificate Validation. CVSS score: 7.0/10. Published 2020-05-12.

How severe is CVE-2020-8156?

High severity. CVSS v3 base score is 7.0 out of 10.

Vulnerability in Nextcloud Mail

CVE-2020-8156

A missing verification of the TLS host in Nextcloud Mail 1.1.3 allowed a man in the middle attack.

Vulnerability class: Improper Certificate Validation

Published 2020-05-12 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:L.

EPSS exploit prediction

EPSS: 0.010 (59.9th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 60th percentile — 59.9% 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: 0.010 · change: +0.000

Affected products

Nextcloud Mail
Fedoraproject Fedora — versions 32
Nextcloud Mail — versions 1.1.4

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

References

nextcloud.com/security/advisory/ (Vendor Advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)

Frequently asked questions

What is CVE-2020-8156?: CVE-2020-8156 is a high-severity vulnerability in Nextcloud Mail, classified under Improper Certificate Validation. CVSS score: 7.0/10. Published 2020-05-12.
How severe is CVE-2020-8156?: High severity. CVSS v3 base score is 7.0 out of 10.