No exploitation reportedFix available

CVE-2019-20853

Q: Is CVE-2019-20853 actively exploited?

Active exploitation of CVE-2019-20853 has not been confirmed. Its EPSS score was 2.2% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2019-20853?

CVE-2019-20853 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2020-06-19
Fixed in5.16.3
WeaknessCWE-668

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

An issue was discovered in Mattermost Packages before 5.16.3. A Droplet could allow Internet access to a service that has a remote code execution problem.

Timeline

dates in UTC

2020-06-1915:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2019-20853?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2019-20853?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Mattermost mattermost packages

Branch	Affected	Fixed in	Source
5.16	< 5.16.3	5.16.3	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Mattermost mattermost packages to 5.16.3

Advisories and patches

mattermost.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.19.8read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
NVDweakness (CWE)CWE-668read 2026-10-23
FIRST EPSSEPSS score2.2 %2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2020-06-19
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2019-20853?

An issue was discovered in Mattermost Packages before 5.16.3. A Droplet could allow Internet access to a service that has a remote code execution problem.

Is CVE-2019-20853 actively exploited?

Active exploitation of CVE-2019-20853 has not been confirmed. Its EPSS score was 2.2% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2019-20853?

CVE-2019-20853 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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