SSRF via unvalidated attachment URLs in Mattermost Agents plugin MCP server
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Mattermost | Mattermost | unaffected |
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Configuration 1 [-]
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No data.
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| Mattermost | Mattermost |
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Vendor Solution
Update Mattermost to versions 11.7.0, 10.11.19, 11.6.4, 11.5.7 or higher.
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.139% probability within 30 days)
| Link | Providers |
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| https://mattermost.com/security-updates |
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| Type | Values Removed | Values Added |
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| First Time appeared |
Mattermost
Mattermost mattermost |
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| Vendors & Products |
Mattermost
Mattermost mattermost |
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| Metrics |
ssvc
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| Description | Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to validate attachment URLs against internal or private IP ranges in the Mattermost Agents plugin MCP server which allows an attacker with access to the MCP server in stdio mode to perform server-side request forgery (SSRF) and exfiltrate data from internal network services via supplying internal URLs as file attachments in post creation requests.. Mattermost Advisory ID: MMSA-2026-00635 | |
| Title | SSRF via unvalidated attachment URLs in Mattermost Agents plugin MCP server | |
| Weaknesses | CWE-918 | |
| References |
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| Metrics |
cvssV3_1
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