PT-2020-8457 · Mattermost · Mattermost Server

Published 2020-06-19 · Updated 2026-03-03 · CVE-2017-18911

Positive Technologies (AI Summary)

CVSS v3.1

9.1

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Name of the Vulnerable Software and Affected Versions: Mattermost Server versions prior to 3.8.2 Mattermost Server versions prior to 3.7.5 Mattermost Server versions prior to 3.6.7

Description: An issue was discovered that allows the X.509 certificate validation to be skipped for a TLS-based e-mail server.

Recommendations: For versions prior to 3.8.2, update to version 3.8.2 or later. For versions prior to 3.7.5, update to version 3.7.5 or later. For versions prior to 3.6.7, update to version 3.6.7 or later.

Fix

Improper Certificate Validation

Weakness Enumeration

CWE-295

Related Identifiers

CVE-2017-18911

GHSA-M462-MQW4-2C8M

GO-2026-4464

SUSE-SU-2026:0757-1

Affected Products

Mattermost Server

References · 117

• https://osv.dev/vulnerability/GO-2026-4464 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2017-18911 · Security Note
• https://osv.dev/vulnerability/SUSE-SU-2026:0757-1 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-m462-mqw4-2c8m · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2017-18911 · Vendor Advisory
• https://mattermost.com/security-updates · Vendor Advisory
• https://github.com/mattermost/mattermost · Note
• https://github.com/mattermost/mattermost/commit/222bce0c5c1abb2f58c3a6de1fe8c5d3accffb21 · Note
• https://github.com/mattermost/mattermost/commit/691c18157025d4808b5b11de1d6de01050e54fa6 · Note
• https://github.com/mattermost/mattermost/commit/e9bb8cdfb4915067349a4840ab15ff941c4eb070 · Note
• https://suse.com/security/cve/CVE-2025-64111 · Note
• https://suse.com/security/cve/CVE-2026-0998 · Note
• https://suse.com/security/cve/CVE-2026-24122 · Note
• https://suse.com/security/cve/CVE-2026-22892 · Note
• https://suse.com/security/cve/CVE-2026-21434 · Note