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TI-2019-15089 Aliases CVE-2019-20871GHSA-q3p5-24hp-vq34

An issue was discovered in Mattermost Server before 5.9.0, 5.8.1, 5.7.3, and 4.10.8.

Priority LOW 35Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
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 5.9.0, 5.8.1, 5.7.3, and 4.10.8. The Markdown library allows catastrophic backtracking.

Why it matters now

EPSS 0.01114 66th 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

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 5

CPEVersionsRoleVendor
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*before 4.10.8; 5.7.0 to before 5.7.3; 5.8.0 to before 5.8.1VulnerableMattermost
cpe:2.3:a:mattermost:mattermost_server:5.9.0:rc1:*:*:*:*:*:*5.9.0 rc1VulnerableMattermost
cpe:2.3:a:mattermost:mattermost_server:5.9.0:rc2:*:*:*:*:*:*5.9.0 rc2VulnerableMattermost
cpe:2.3:a:mattermost:mattermost_server:5.9.0:rc3:*:*:*:*:*:*5.9.0 rc3VulnerableMattermost
cpe:2.3:a:mattermost:mattermost_server:5.9.0:rc4:*:*:*:*:*:*5.9.0 rc4VulnerableMattermost
  • cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* Versions before 4.10.8; 5.7.0 to before 5.7.3; 5.8.0 to before 5.8.1 Vulnerable ·Mattermost
  • cpe:2.3:a:mattermost:mattermost_server:5.9.0:rc1:*:*:*:*:*:* Versions 5.9.0 rc1 Vulnerable ·Mattermost
  • cpe:2.3:a:mattermost:mattermost_server:5.9.0:rc2:*:*:*:*:*:* Versions 5.9.0 rc2 Vulnerable ·Mattermost
  • cpe:2.3:a:mattermost:mattermost_server:5.9.0:rc3:*:*:*:*:*:* Versions 5.9.0 rc3 Vulnerable ·Mattermost
  • cpe:2.3:a:mattermost:mattermost_server:5.9.0:rc4:*:*:*:*:*:* Versions 5.9.0 rc4 Vulnerable ·Mattermost

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2019-20871
  2. 2026-10-03 Alias added: GHSA-q3p5-24hp-vq34

References

Advisory 1

  • 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
See all 505 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences