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TI-2026-07749 Aliases CVE-2026-8823GHSA-xmfh-3ccg-c9fx

User Manager can demote bot accounts to guest without bot-management permission

Priority LOW 18CWE-863Published · Updated

Key facts

Attack vector
Network
Privileges required
High
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
None · Low · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-863.

Summary

Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Mattermost Advisory ID: MMSA-2026-00669

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00318 24th percentileScored 2026-11-07
Fix Fixed Mattermost (Mattermost): 11.8.0, 11.7.1, 10.11.18github.com/mattermost/mattermost-server (Go): 11.7.1, 10.11.18+1 more product

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MattermostMattermost11.7.0 – 11.7.0; 10.11.0 – 10.11.1711.8.0, 11.7.1, 10.11.18Patch availableCNA
—github.com/mattermost/mattermost-server (Go)11.7.0 to before 11.7.111.7.1Patch availableGHSA-xmfh-3ccg-c9fx
—github.com/mattermost/mattermost-server (Go)10.11.0 to before 10.11.1810.11.18Patch availableGHSA-xmfh-3ccg-c9fx
—github.com/mattermost/mattermost/server/v8 (Go)before 8.0.0-20260518160100-9bd77d3fc4d28.0.0-20260518160100-9bd77d3fc4d2Patch availableGHSA-xmfh-3ccg-c9fx
  • Mattermost VendorMattermost Affected 11.7.0 – 11.7.0; 10.11.0 – 10.11.17 Fixed in 11.8.0, 11.7.1, 10.11.18 Patch available CNA
  • github.com/mattermost/mattermost-server (Go) Vendor— Affected 11.7.0 to before 11.7.1 Fixed in 11.7.1 Patch available GHSA-xmfh-3ccg-c9fx
  • github.com/mattermost/mattermost-server (Go) Vendor— Affected 10.11.0 to before 10.11.18 Fixed in 10.11.18 Patch available GHSA-xmfh-3ccg-c9fx
  • github.com/mattermost/mattermost/server/v8 (Go) Vendor— Affected before 8.0.0-20260518160100-9bd77d3fc4d2 Fixed in 8.0.0-20260518160100-9bd77d3fc4d2 Patch available GHSA-xmfh-3ccg-c9fx

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*10.11.0 to before 10.11.18; 11.7.0 to before 11.7.1VulnerableMattermost
  • cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* Versions 10.11.0 to before 10.11.18; 11.7.0 to before 11.7.1 Vulnerable ·Mattermost

Remediation

  • Fix · CNA Mattermost (Mattermost) Fixed in 11.8.0, 11.7.1, 10.11.18
  • Fix · GHSA-xmfh-3ccg-c9fx github.com/mattermost/mattermost-server (Go) Fixed in 11.7.1 Advisory →
  • Fix · GHSA-xmfh-3ccg-c9fx github.com/mattermost/mattermost-server (Go) Fixed in 10.11.18 Advisory →
  • Fix · GHSA-xmfh-3ccg-c9fx github.com/mattermost/mattermost/server/v8 (Go) Fixed in 8.0.0-20260518160100-9bd77d3fc4d2 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-8823
  2. 2026-10-03 Alias added: GHSA-xmfh-3ccg-c9fx

References

Advisory 2

Other 9

  • 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