Mattermost 10.9
Mattermost 10.9
The Mattermost 10.9 reached end of service life on Sep 15, 2025 — Mattermost no longer ships security patches or fixes for it. Our third-party support keeps it safe to run: 24/7 engineers manage issues, remediate vulnerabilities, and help you maintain compliance.
24/7 engineers own your Mattermost 10.9 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
- 10.9
- product Label
- Mattermost
- release Label
- 10.9
- codename
- lts
- latest Version
- 10.9.5
- release Date
- 2025-06-16
- maintained
- source Url
- https://endoflife.date/mattermost
Lifecycle Dates
- End of Service Life
- Sep 15, 2025
- Last OEM Support
- Sep 15, 2025
OEM vs. 3rd Party Support
See how third-party support compares to the vendor contract for Mattermost 10.9 — 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 10.9?
Vulnerability Remediation
Scanning, mitigation and patch-around guidance for Mattermost 10.9 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 10.9 Support: Frequently Asked Questions
Is the Mattermost 10.9 still supported?
Mattermost ended support for the Mattermost 10.9 on Sep 15, 2025 — no more patches or fixes from the vendor. Third-party support keeps it covered: our engineers manage issues, remediate vulnerabilities, and help you maintain compliance for as long as you run it.
When is the Mattermost 10.9 end of service life (EOSL) date?
Mattermost lists the end of service life for the Mattermost 10.9 as Sep 15, 2025.
Can I keep using the Mattermost 10.9 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 10.9 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 10.9
13 published CVEs affect the Mattermost 10.9, including 2 rated critical or high severity. Mattermost no longer ships security patches for this release — our engineers provide mitigation guidance, workarounds and hardening support.
| CVE | Severity | CVSS | Published | Summary |
|---|---|---|---|---|
| CVE-2025-9079 | HIGH | 8.0 | Sep 19, 2025 | Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.1, 10.9.x <= 10.9.3 fail to validate import directory path configuration which allows admin users to execute arbitrary code via malicious plugin upload to prepackaged plugins directory |
| CVE-2025-9072 | HIGH | 7.6 | Sep 15, 2025 | Mattermost versions 10.10.x <= 10.10.1, 10.5.x <= 10.5.9, 10.9.x <= 10.9.4 fail to validate the redirect_to parameter, allowing an attacker to craft a malicious link that, once a user authenticates with their SAML provider, could post the user’s cookies to an attacker-controlled URL. |
| CVE-2025-8023 | MEDIUM | 6.8 | Aug 21, 2025 | Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin to perform path traversal attacks via malicious path components, potentially enabling malicious file placement outside intended directories. |
| CVE-2025-49222 | MEDIUM | 6.8 | Aug 21, 2025 | Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2, 10.10.x <= 10.10.0 fail to validate upload types in remote cluster upload sessions which allows a system admin to upload non-attachment file types via shared channels that could potentially be placed in arbitrary filesystem directories. |
| CVE-2025-36530 | MEDIUM | 6.8 | Aug 21, 2025 | Mattermost versions 10.9.x <= 10.9.1, 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate file paths during plugin import operations which allows restricted admin users to install unauthorized custom plugins via path traversal in the import functionality, bypassing plugin signature enforcement and marketplace restrictions. |
| CVE-2025-55070 | MEDIUM | 6.5 | Nov 14, 2025 | Mattermost versions <11 fail to enforce multi-factor authentication on WebSocket connections which allows unauthenticated users to access sensitive information via WebSocket events |
| CVE-2025-8402 | MEDIUM | 4.9 | Aug 21, 2025 | Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to validate import data which allows a system admin to crash the server via the bulk import feature. |
| CVE-2026-2461 | MEDIUM | 4.3 | Mar 16, 2026 | Mattermost Plugins versions <=11.3 11.0.3 11.2.2 10.10.11.0 fail to implement authorisation checks on comment block modifications, which allows an authorised attacker with editor permission to modify comments created by other board members. Mattermost Advisory ID: MMSA-2025-00559 |
| CVE-2025-11776 | MEDIUM | 4.3 | Nov 14, 2025 | Mattermost versions <11 fail to properly restrict access to archived channel search API which allows guest users to discover archived public channels via the `/api/v4/teams/{team_id}/channels/search_archived` endpoint |
| CVE-2025-9078 | MEDIUM | 4.3 | Sep 15, 2025 | Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.1, 10.9.x <= 10.9.3 fail to properly validate cache keys for link metadata which allows authenticated users to access unauthorized posts and poison link previews via hash collision attacks on FNV-1 hashing |
| CVE-2025-6465 | MEDIUM | 4.3 | Aug 21, 2025 | Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to sanitize file names which allows users with file upload permission to overwrite file attachment thumbnails via path traversal in file streaming APIs. |
| CVE-2025-47870 | MEDIUM | 4.3 | Aug 21, 2025 | Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fail to sanitize the team invite ID in the POST /api/v4/teams/:teamId/restore endpoint which allows an team admin with no member invite privileges to get the team’s invite id. |
| CVE-2025-41436 | LOW | 3.1 | Nov 14, 2025 | Mattermost versions <11.0 fail to properly enforce the "Allow users to view archived channels" setting which allows regular users to access archived channel content and files via the "Open in Channel" functionality from followed threads |