PT-2020-8435 · Mattermost · Mattermost Server

Published 2020-06-19 · Updated 2026-01-06 · CVE-2017-18889

Positive Technologies (AI Summary)

CVSS v3.1

4.3

Medium

Base vector

AV:N/AC:L/PR:L/UI:N/S:U/C:N/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 in Mattermost Server. An attacker could create fictive system-message posts via webhooks and slash commands, in the v3 or v4 REST API.

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. As a temporary workaround, consider restricting access to the v3 and v4 REST API endpoints until a patch is available. Avoid using webhooks and slash commands in the affected API versions until the issue is resolved.

Fix

RCE

Weakness Enumeration

CWE-20

Related Identifiers

CVE-2017-18889

GHSA-JP57-4X34-5V94

GO-2025-4201

SUSE-SU-2026:0037-1

Affected Products

Mattermost Server

References · 85

• https://osv.dev/vulnerability/GO-2025-4201 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:0037-1 · Vendor Advisory
• https://mattermost.com/security-updates · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2017-18889 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2017-18889 · Security Note
• https://suse.com/security/cve/CVE-2017-18889 · Note
• https://suse.com/security/cve/CVE-2025-0426 · Note
• https://suse.com/security/cve/CVE-2025-68938 · Note
• https://suse.com/security/cve/CVE-2017-18886 · Note
• https://suse.com/security/cve/CVE-2025-34430 · Note
• https://suse.com/security/cve/CVE-2025-62190 · Note
• https://suse.com/security/cve/CVE-2024-41260 · Note
• https://suse.com/security/cve/CVE-2025-47913 · Note
• https://suse.com/security/cve/CVE-2017-18888 · Note
• https://suse.com/security/cve/CVE-2025-13352 · Note