CVE-2026-4339
Mattermost
- Severity
- Medium
- Published
- June 26, 2026
- Last modified
- June 29, 2026
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
CVSS vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Weakness
- CWE-918 Server-side request forgery
References
- mattermost.comVendor Advisory
Listed in
Related CVEs
The officially documented Azure one-click deployment uses infrastructure/azuredeploy.json and infrastructure/main.bicep to default the apiKey parameter to an empty string and pass it to the App Service…
Trigger.dev cli-v3 from 3.0.0 before 4.5.4 contains a missing authentication vulnerability in the trigger dev --mcp server, which binds all network interfaces and exposes the /sse and /messages endpoints.
IBM ContextForge MCP Gateway 0.1.0 through 1.0.5 is vulnerable to a server-side request Forgery (SSRF) that allows authenticated users with gateway creation privileges to perform arbitrary HTTP POST…
djust provides Phoenix LiveView-style reactive server-side rendering for Django with Rust-powered performance.
A security flaw has been discovered in mcollina mcp-ripgrep up to 0.4.0.
The experimental tasks feature (taskStore) did not check which session created a task.