One-Click Mattermost Account Takeover via Poisoned RelayState SAML Parameter
Published Sep 15, 2025
7.6
HIGHCVSS 3.1
EPSS 0.17%
Description
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.
Affected products
-
- Version 10.10.0StatusaffectedConstraints<=10.10.1
- Version 10.5.0StatusaffectedConstraints<=10.5.9
- Version 10.9.0StatusaffectedConstraints<=10.9.4
- Version 10.10.2StatusunaffectedConstraints-
- Version 10.11.0StatusunaffectedConstraints-
- Version 10.5.10StatusunaffectedConstraints-
- Version 10.9.5StatusunaffectedConstraints-
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mattermost | Mattermost | unaffected |
|
- ≥ 10.5.0 · < 10.5.10
- ≥ 10.9.0 · < 10.9.5
- ≥ 10.10.0 · < 10.10.2
No data.
No Red Hat product state for this CVE.
github.com/mattermost/mattermost/server/v8
Go
Introduced 0 Fixed 8.0.0-20250731063404-9eebaadf8f72github.com/mattermost/mattermost-server/v5
Go
Introduced 0 Fixed not fixedgithub.com/mattermost/mattermost-server/v6
Go
Introduced 0 Fixed not fixedgithub.com/mattermost/mattermost-server
Go
Introduced 10.5.0+incompatible Fixed 10.5.10+incompatiblegithub.com/mattermost/mattermost-server
Go
Introduced 10.9.0+incompatible Fixed 10.9.5+incompatiblegithub.com/mattermost/mattermost-server
Go
Introduced 10.10.0+incompatible Fixed 10.10.2+incompatible
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Go | github.com/mattermost/mattermost/server/v8 | 0 | 8.0.0-20250731063404-9eebaadf8f72 |
| Go | github.com/mattermost/mattermost-server/v5 | 0 | not fixed |
| Go | github.com/mattermost/mattermost-server/v6 | 0 | not fixed |
| Go | github.com/mattermost/mattermost-server | 10.5.0+incompatible | 10.5.10+incompatible |
| Go | github.com/mattermost/mattermost-server | 10.9.0+incompatible | 10.9.5+incompatible |
| Go | github.com/mattermost/mattermost-server | 10.10.0+incompatible | 10.10.2+incompatible |
Remediation
Vendor solution
Update Mattermost to versions 10.11.0, 10.10.2, 10.5.10, 10.9.5 or higher.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
1 other source (GHSA) ▾
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:L
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
TotalDecision
n/aAssessed Sep 15, 2025 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 4, 2026.
Score over time
2025-2026- EPSS v4
- EPSS v5
Percentile over time
- EPSS v4
- EPSS v5
Table of values (3 key points)
Flat stretches are collapsed. Showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 4, 2026 | 0.17% (0.00172) | 5.97th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.16% (0.00161) | 5.63th | v5 (v2026.06.15) |
| Sep 15, 2025 | 0.04% (0.00038) | 10.25th | v4 (v2025.03.14) |
References (6)
- https://github.com/advisories/GHSA-69j8-prx2-vx98 Advisory
- https://github.com/mattermost/mattermost/commit/13cd76009d31754db46115bddef5287a8a29871a
- https://github.com/mattermost/mattermost/commit/9eebaadf8f720788e99b6997337c8df330271326
- https://github.com/mattermost/mattermost/commit/fda403fb6ec41bea8780bff198a26860f105e6e5
- https://mattermost.com/security-updates Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2025-9072
Change history (0)
No recorded changes yet.