PT-2020-8452 · Mattermost · Mattermost Server

Published 2020-06-19 · Updated 2026-03-03 · CVE-2017-18906

Positive Technologies (AI Summary)

CVSS v3.1

8.1

High

Base vector

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

Name of the Vulnerable Software and Affected Versions: Mattermost Server versions prior to 4.0.0 Mattermost Server version 3.10.2 Mattermost Server version 3.9.2

Description: An issue was discovered when Single Sign-On OAuth2 is used, allowing an attacker to claim somebody else's account.

Recommendations: For Mattermost Server versions prior to 4.0.0, update to version 4.0.0 or later. For Mattermost Server version 3.10.2, update to version 4.0.0 or later. For Mattermost Server version 3.9.2, update to version 4.0.0 or later.

Fix

Improper Authentication

Insufficient Session Expiration

Weakness Enumeration

CWE-287

CWE-613

Related Identifiers

CVE-2017-18906

GHSA-FPCR-4RR5-HPCP

GO-2026-4477

SUSE-SU-2026:0757-1

Affected Products

Mattermost Server

References · 118

• https://osv.dev/vulnerability/GHSA-fpcr-4rr5-hpcp · Vendor Advisory
• https://osv.dev/vulnerability/GO-2026-4477 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2017-18906 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:0757-1 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2017-18906 · Security Note
• https://mattermost.com/security-updates · Vendor Advisory
• https://github.com/mattermost/mattermost · Note
• https://github.com/mattermost/mattermost/commit/259ad46f30d0fac2f7c5c14f3b76b2170f7e90c7 · Note
• https://github.com/mattermost/mattermost/commit/fbc170733e86f09b46ba754dd03304733d2f482f · Note
• https://github.com/mattermost/mattermost/commit/b17fca0d5ee7557e3df1cf1d1da8bd749859e35f · 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