PT-2020-8443 · Mattermost · Mattermost Server

Published 2020-06-19 · Updated 2026-01-17 · CVE-2017-18897

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 4.2.0 Mattermost Server version 4.1.1 Mattermost Server version 4.0.5

Description: The issue concerns Mattermost Server when used as an OAuth 2.0 service provider. It mishandles a deny action for a redirection.

Recommendations: For versions prior to 4.2.0, update to version 4.2.0 or later. For version 4.1.1, update to version 4.2.0 or later. For version 4.0.5, update to version 4.2.0 or later.

Fix

Open Redirect

Weakness Enumeration

CWE-601

Related Identifiers

CVE-2017-18897

GHSA-F7C3-7VP3-44P6

GO-2026-4301

SUSE-SU-2026:0142-1

Affected Products

Mattermost Server

References · 45

• https://osv.dev/vulnerability/CVE-2017-18897 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2017-18897 · Security Note
• https://osv.dev/vulnerability/GO-2026-4301 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-f7c3-7vp3-44p6 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:0142-1 · Vendor Advisory
• https://mattermost.com/security-updates · Vendor Advisory
• https://github.com/mattermost/mattermost · Note
• https://github.com/mattermost/mattermost/commit/d38328976e2c8bb0fab91e656042a0d8ac37bc76 · Note
• https://github.com/mattermost/mattermost/commit/722fb1947a2e7395ccf16adce9206736d803a9f3 · Note
• https://github.com/mattermost/mattermost/commit/3c34e2b2dcb0fde96a10e68d877aa7d0ab511669 · Note
• https://suse.com/security/cve/CVE-2026-22688 · Note
• https://suse.com/security/cve/CVE-2026-21859 · Note
• https://suse.com/support/update/announcement/2026/suse-su-20260142-1 · Note
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-18897 · Note
• https://suse.com/security/cve/CVE-2026-22703 · Note