PT-2020-8455 · Mattermost · Mattermost Server

Published 2020-06-19 · Updated 2026-03-03 · CVE-2017-18909

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

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

Name of the Vulnerable Software and Affected Versions: Mattermost Server versions prior to 3.9.0

Description: An issue was discovered when SAML is used, where encryption and signature verification are not mandatory.

Recommendations: For versions prior to 3.9.0, update to version 3.9.0 or later to resolve the issue.

Fix

Missing Encryption of Sensitive Data

Improper Verification of Cryptographic Signature

Improper Certificate Validation

Weakness Enumeration

CWE-311

CWE-347

CWE-295

Related Identifiers

CVE-2017-18909

GHSA-R6J5-FQX9-7QV9

GO-2026-4478

SUSE-SU-2026:0757-1

Affected Products

Mattermost Server

References · 115

• https://osv.dev/vulnerability/SUSE-SU-2026:0757-1 · Vendor Advisory
• https://osv.dev/vulnerability/GO-2026-4478 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-r6j5-fqx9-7qv9 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2017-18909 · Security Note
• https://mattermost.com/security-updates · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2017-18909 · Vendor Advisory
• https://github.com/mattermost/mattermost · Note
• https://github.com/mattermost/mattermost/commit/4f074fed0d653a28779ac586e418341232d43e95 · 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-2026-22892 · Note
• https://suse.com/security/cve/CVE-2026-24122 · Note
• https://suse.com/security/cve/CVE-2026-21434 · Note
• https://suse.com/security/cve/CVE-2026-25760 · Note
• https://suse.com/security/cve/CVE-2025-13821 · Note