An issue was discovered in Mattermost Server before 5.16.1, 5.15.2, 5.14.5, and 5.9.6.
Priority LOW 35Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
An issue was discovered in Mattermost Server before 5.16.1, 5.15.2, 5.14.5, and 5.9.6. It allows attackers to obtain sensitive information (local files) during legacy attachment migration.
Why it matters now
EPSS 0.01163 67th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* | before 5.9.6; 5.14.0 to before 5.14.5; 5.15.0 to before 5.15.2; 5.16.0 to before 5.16.1 | Vulnerable | Mattermost |
- cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* Versions before 5.9.6; 5.14.0 to before 5.14.5; 5.15.0 to before 5.15.2; 5.16.0 to before 5.16.1 Vulnerable ·Mattermost
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2019-20855
- 2026-10-03 Alias added: GHSA-ggg2-74c2-pvrh
References
Advisory 1
More Mattermost Server vulnerabilities
- TI-2025-18933 Arbitrary file read in Mattermost Boards via import & export board archive CVSS 3.1CRITICAL 9.9
- TI-2025-04465 Path Traversal Leading to RCE by Any Authenticated Mattermost User CVSS 3.1CRITICAL 9.9
- TI-2017-14068 An issue was discovered in Mattermost Server before 3.6.2. CVSS 3.1CRITICAL 9.8
- TI-2017-14060 An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. CVSS 3.1CRITICAL 9.8
- TI-2017-14048 An issue was discovered in Mattermost Server before 4.1.0, 4.0.4, and 3.10.3. CVSS 3.1CRITICAL 9.8
- TI-2025-14360 Arbitrary file read via block duplication in Mattermost Boards CVSS 3.1CRITICAL 9.9
Sources
- CVE-2019-20855 · CVE Program
- CVE-2019-20855 · NVD
- FIRST EPSS
- GHSA-ggg2-74c2-pvrh · GitHub Advisory Database · CC BY 4.0
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