Mattermost 11.8
Mattermost 11.8
The Mattermost 11.8 reaches end of service life on Sep 15, 2026. Third-party support keeps it managed past that date — issue management, vulnerability remediation, and compliance maintenance from 24/7 engineers.
24/7 engineers own your Mattermost 11.8 incidents end to end.
Mitigation and patch-around guidance when the vendor no longer ships fixes.
Controls evidence and documentation that keep auditors satisfied.
Specifications
- product
- mattermost
- release
- 11.8
- product Label
- Mattermost
- release Label
- 11.8
- codename
- lts
- latest Version
- 11.8.5
- release Date
- 2026-06-16
- maintained
- true
- source Url
- https://endoflife.date/mattermost
Lifecycle Dates
- End of Service Life
- Sep 15, 2026
- Last OEM Support
- Sep 15, 2026
OEM vs. 3rd Party Support
See how third-party support compares to the vendor contract for Mattermost 11.8 — monitoring, break/fix, vulnerability work, operations and compliance, before and after EOSL.
| Feature | OEM Support | 3rd Party Support |
|---|---|---|
| Post-EOSL Support | ||
| Break/Fix Support | Until EOSL | |
| 24/7 Monitoring | ||
| Vulnerability Scanning & Remediation | ||
| Managed Operations | ||
| Procedure & Configuration Review | ||
| Compliance & Audit Documentation | Limited | |
| Discounted Migration to Other Platforms |
Why Choose 3rd Party Support for Mattermost 11.8?
Vulnerability Remediation
Scanning, mitigation and patch-around guidance for Mattermost 11.8 when the vendor no longer ships fixes.
Compliance Maintenance
Procedure review, controls evidence and the documentation auditors ask for — maintained continuously, not scrambled at audit time.
24/7 Expert Support
Engineers who know this release monitor, manage and fix issues around the clock — break/fix to managed operations.
Mattermost 11.8 Support: Frequently Asked Questions
Is the Mattermost 11.8 still supported?
Yes, but Mattermost support for the Mattermost 11.8 ends on Sep 15, 2026. You can upgrade on the vendor's schedule, or move to third-party support and keep the release you're on — issues managed, vulnerabilities remediated, compliance maintained.
When is the Mattermost 11.8 end of service life (EOSL) date?
Mattermost lists the end of service life for the Mattermost 11.8 as Sep 15, 2026.
Can I keep using the Mattermost 11.8 after its EOSL date?
Yes. EOSL means Mattermost stops issuing patches and support — the software itself keeps running. Third-party support covers it from there: issue management, security vulnerability remediation, and the compliance documentation auditors ask for, for as long as you choose to run it.
How much does third-party support for the Mattermost 11.8 cost?
Typically 40-70% below the OEM maintenance renewal price. Exact pricing depends on quantity, service level and location — request a quote and we respond within 24 hours.
Known Vulnerabilities Affecting Mattermost 11.8
11 published CVEs affect the Mattermost 11.8, including 1 rated critical or high severity. Our 24/7 engineers help you assess exposure, prioritize fixes and apply available patches.
| CVE | Severity | CVSS | Published | Summary |
|---|---|---|---|---|
| CVE-2026-9816 | HIGH | 8.3 | Aug 17, 2026 | Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate BoardMember.Scheme* fields server-side on insert and archive-import paths which allows a board editor or non-guest team member to grant board admin to arbitrary users via POST /api/v2/boards/{boardID}/members and POST /api/v2/teams/{teamID}/archive/import.. Mattermost Advisory ID: MMSA-2026-00685 |
| CVE-2026-9859 | MEDIUM | 6.5 | Aug 17, 2026 | Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to enforce PermissionManageBoardRoles on the channelId field of the batch endpoint, which allows an authenticated board editor to relink any board they can edit to an arbitrary channel via a crafted PATCH request. Mattermost Advisory ID: MMSA-2026-00686 |
| CVE-2026-10080 | MEDIUM | 6.5 | Aug 17, 2026 | Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to validate WebSocket command field types which allows an authenticated user to crash the plugin process and deny service to all Boards users via a custom_focalboard_SUBSCRIBE_TEAM message with a non-string teamId.. Mattermost Advisory ID: MMSA-2026-00687 |
| CVE-2026-14298 | MEDIUM | 6.5 | Aug 13, 2026 | Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to properly limit resource consumption when processing certain user-supplied input, which allows an authenticated user to cause a denial of service. Mattermost Advisory ID: MMSA-2026-00713 |
| CVE-2026-10819 | MEDIUM | 6.5 | Jul 27, 2026 | Mattermost versions 11.6.x <= 11.6.5, 10.11.x <= 10.11.20, 11.8.x <= 11.8.1, 11.7.x <= 11.7.4 fail to limit the number of frames and enforce the file size cap on animated GIF uploads, which allows an authenticated attacker to cause a denial of service via a crafted animated GIF uploaded as a custom emoji.. Mattermost Advisory ID: MMSA-2026-00695 |
| CVE-2026-16048 | MEDIUM | 6.3 | Aug 17, 2026 | Mattermost versions 11.8.x <= 11.8.2, 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to restrict channel member role assignment to channel-scoped roles which allows a channel administrator to gain additional channel permissions via the channel member roles API.. Mattermost Advisory ID: MMSA-2026-00697 |
| CVE-2026-10527 | MEDIUM | 6.3 | Aug 17, 2026 | Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to reconcile SchemeAdmin flags with a user's current role which allows a user demoted to System Guest to retain Board Admin privileges and perform admin-only operations via the Boards REST API or UI.. Mattermost Advisory ID: MMSA-2026-00691 |
| CVE-2026-7521 | MEDIUM | 5.5 | Jul 28, 2026 | Mattermost versions 11.8.x <= 11.8.0, 11.7.x <= 11.7.3, 11.6.x <= 11.6.5, 10.11.x <= 10.11.20 fail to verify file deletion path which allows an admin with SAML system-console write permissions to delete arbitrary files outside the config directory from the server via the remove file endpoint.. Mattermost Advisory ID: MMSA-2026-00666 |
| CVE-2026-16047 | MEDIUM | 4.3 | Aug 17, 2026 | Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate that users have read access to a channel before linking a board to it, which allows an authenticated attacker to discover the membership of private channels on the same team via creating, patching, importing, or bulk-creating boards with an arbitrary channelId. Mattermost Advisory ID: MMSA-2026-00674 |
| CVE-2026-10600 | MEDIUM | 4.3 | Jul 27, 2026 | Mattermost versions 11.8.x <= 11.8.0, 11.7.x <= 11.7.3, 11.6.x <= 11.6.5, 10.11.x <= 10.11.20 fail to bound the time and resource consumption of server-side document content extraction which allows an authenticated user with file-upload permission to degrade file uploads for all users on the server via repeatedly uploading small documents that are cheap to upload but expensive to extract, saturating the shared extraction worker pool.. Mattermost Advisory ID: MMSA-2026-00694 |
| CVE-2026-15754 | MEDIUM | 4.2 | Aug 17, 2026 | Mattermost versions 11.7.x <= 11.7.6, 11.8.x <= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718 |