PT-2020-8423 · Mattermost · Mattermost Server

Published 2020-06-19 · Updated 2025-12-15 · CVE-2017-18877

Positive Technologies (AI Summary)

CVSS v3.1

6.1

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions: Mattermost Server versions prior to 4.3.0 Mattermost Server version 4.2.1 Mattermost Server version 4.1.2

Description: An issue was discovered that allows XSS attacks to occur against an OAuth 2.0 allow/deny page.

Recommendations: For versions prior to 4.3.0, update to version 4.3.0 or later. For version 4.2.1, update to version 4.3.0 or later. For version 4.1.2, update to version 4.3.0 or later.

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2017-18877

GHSA-9X8X-W6G5-HX4W

GO-2025-4190

SUSE-SU-2025:4395-1

Affected Products

Mattermost Server

References · 45

• https://nvd.nist.gov/vuln/detail/CVE-2017-18877 · Security Note
• https://mattermost.com/security-updates · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2017-18877 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2025:4395-1 · Vendor Advisory
• https://osv.dev/vulnerability/GO-2025-4190 · Vendor Advisory
• https://suse.com/security/cve/CVE-2017-18884 · Note
• https://suse.com/security/cve/CVE-2017-18871 · Note
• https://suse.com/security/cve/CVE-2025-12756 · Note
• https://suse.com/security/cve/CVE-2025-65025 · Note
• https://suse.com/security/cve/CVE-2025-13870 · Note
• https://suse.com/security/cve/CVE-2025-66564 · Note
• https://github.com/advisories/GHSA-9x8x-w6g5-hx4w · Note
• https://suse.com/security/cve/CVE-2025-61727 · Note
• https://suse.com/security/cve/CVE-2025-64443 · Note
• https://suse.com/security/cve/CVE-2025-13353 · Note