Race Condition in Guest Magic Link Authentication Allows Token Reuse
Priority LOW 34CWE-367Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.
Summary
Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to enforce atomic single-use consumption of guest magic link tokens, which allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions via concurrent requests.. Mattermost Advisory ID: MMSA-2026-00624
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00152 4th percentileScored 2026-11-07
Fix Fixed Mattermost (Mattermost): 11.6.0, 10.11.13, 11.5.1 +2github.com/mattermost/mattermost/server/v8 (Go): 8.0.0-20250723052842-4cb8d8940332+1 more product
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Mattermost | Mattermost | 10.11.0 – 10.11.12; 11.5.0 – 11.5.0; 11.4.0 – 11.4.2; 11.3.0 – 11.3.2 | 11.6.0, 10.11.13, 11.5.1, 11.4.3, 11.3.3 | Patch available | CNA |
| — | github.com/mattermost/mattermost/server/v8 (Go) | 8.0.0-20250721062209-4952acea88ce to before 8.0.0-20250723052842-4cb8d8940332 | 8.0.0-20250723052842-4cb8d8940332 | Patch available | GHSA-mh4x-rmrx-3hp4 |
| — | github.com/mattermost/mattermost-server (Go) | 10.11.0-rc1 to before 10.11.13 | 10.11.13 | Patch available | GHSA-mh4x-rmrx-3hp4 |
| — | github.com/mattermost/mattermost-server (Go) | 11.5.0-rc1 to before 11.5.0 | 11.5.0 | Patch available | GHSA-mh4x-rmrx-3hp4 |
| — | github.com/mattermost/mattermost-server (Go) | 11.4.0-rc1 to before 11.4.3 | 11.4.3 | Patch available | GHSA-mh4x-rmrx-3hp4 |
| — | github.com/mattermost/mattermost-server (Go) | 11.3.0-rc1 to before 11.3.3 | 11.3.3 | Patch available | GHSA-mh4x-rmrx-3hp4 |
- Mattermost VendorMattermost Affected 10.11.0 – 10.11.12; 11.5.0 – 11.5.0; 11.4.0 – 11.4.2; 11.3.0 – 11.3.2 Fixed in 11.6.0, 10.11.13, 11.5.1, 11.4.3, 11.3.3 Patch available CNA
- github.com/mattermost/mattermost/server/v8 (Go) Vendor— Affected 8.0.0-20250721062209-4952acea88ce to before 8.0.0-20250723052842-4cb8d8940332 Fixed in 8.0.0-20250723052842-4cb8d8940332 Patch available GHSA-mh4x-rmrx-3hp4
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 10.11.0-rc1 to before 10.11.13 Fixed in 10.11.13 Patch available GHSA-mh4x-rmrx-3hp4
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 11.5.0-rc1 to before 11.5.0 Fixed in 11.5.0 Patch available GHSA-mh4x-rmrx-3hp4
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 11.4.0-rc1 to before 11.4.3 Fixed in 11.4.3 Patch available GHSA-mh4x-rmrx-3hp4
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 11.3.0-rc1 to before 11.3.3 Fixed in 11.3.3 Patch available GHSA-mh4x-rmrx-3hp4
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* | 10.11.0 to before 10.11.13; 11.3.0 to before 11.3.3; 11.4.0 to before 11.4.3; 11.5.0 to before 11.5.1 | Vulnerable | Mattermost |
- cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* Versions 10.11.0 to before 10.11.13; 11.3.0 to before 11.3.3; 11.4.0 to before 11.4.3; 11.5.0 to before 11.5.1 Vulnerable ·Mattermost
Remediation
- Fix · CNA Mattermost (Mattermost) Fixed in 11.6.0, 10.11.13, 11.5.1, 11.4.3, 11.3.3
- Fix · GHSA-mh4x-rmrx-3hp4 github.com/mattermost/mattermost/server/v8 (Go) Fixed in 8.0.0-20250723052842-4cb8d8940332 Advisory →
- Fix · GHSA-mh4x-rmrx-3hp4 github.com/mattermost/mattermost-server (Go) Fixed in 10.11.13 Advisory →
- Fix · GHSA-mh4x-rmrx-3hp4 github.com/mattermost/mattermost-server (Go) Fixed in 11.5.0 Advisory →
- Fix · GHSA-mh4x-rmrx-3hp4 github.com/mattermost/mattermost-server (Go) Fixed in 11.4.3 Advisory →
- Fix · GHSA-mh4x-rmrx-3hp4 github.com/mattermost/mattermost-server (Go) Fixed in 11.3.3 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-3590
- 2026-10-03 Alias added: GHSA-mh4x-rmrx-3hp4
References
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-2026-3590 · CVE Program
- CVE-2026-3590 · NVD
- FIRST EPSS
- GHSA-mh4x-rmrx-3hp4 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-3590 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences