What is CVE-2019-20856?

CVE-2019-20856 is a critical-severity vulnerability in Apple macOS, classified under Uncontrolled Search Path Element. CVSS score: 9.8/10. Published 2020-06-19.

How severe is CVE-2019-20856?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in Apple macOS

CVE-2019-20856

An issue was discovered in Mattermost Desktop App before 4.3.0 on macOS. It allows dylib injection.

Published 2020-06-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.014 (72.2th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 72nd percentile — 72.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-427 — Uncontrolled Search Path Element

References

mattermost.com/security-updates/ (Vendor Advisory)

Frequently asked questions

What is CVE-2019-20856?: CVE-2019-20856 is a critical-severity vulnerability in Apple macOS, classified under Uncontrolled Search Path Element. CVSS score: 9.8/10. Published 2020-06-19.
How severe is CVE-2019-20856?: Critical severity. CVSS v3 base score is 9.8 out of 10.