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CVE-2026-39417

MaxKB: RCE via MCP stdio command injection in workflow engine

4.6 Medium

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain an incomplete fix for CVE-2025-53928, where a Remote Code Execution vulnerability still exists in the MCP node of the workflow engine. MaxKB only restricts the referencing code path (loading MCP config from the database). The else branch, responsible for loading mcp_servers directly from user-supplied JSON remains completely unpatched. Since mcp_source is an optional field (required=False), an attacker can simply omit it or set it to any non-referencing value to bypass the fix. By calling the workflow creation API directly with a crafted JSON payload, an attacker can inject a complete MCP node configuration with stdio transport, arbitrary command, and args — achieving RCE when the workflow is triggered via chat. This issue has been fixed in version 2.8.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
Low
User interaction
Required

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
Low

Exploit likelihood

0.24%Up 0.2 points since Apr 14, 2026
90%50%10%1%

What each source reports

CVE List Score used 4.6

MaxKB: RCE via MCP stdio command injection in workflow engine

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain an incomplete fix for CVE-2025-53928, where a Remote Code Execution vulnerability still exists in the MCP node of the workflow engine. MaxKB only restricts the referencing code path (loading MCP config from the database). The else branch, responsible for loading mcp_servers directly from user-supplied JSON remains completely unpatched. Since mcp_source is an optional field (required=False), an attacker can simply omit it or set it to any non-referencing value to bypass the fix. By calling the workflow creation API directly with a crafted JSON payload, an attacker can inject a complete MCP node configuration with stdio transport, arbitrary command, and args — achieving RCE when the workflow is triggered via chat. This issue has been fixed in version 2.8.0.

Record
CVE-2026-39417
CVSS 3.1
4.6 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L
Weakness
CWE-78, CWE-20
Updated
2026-11-02
EUVDEUVD-2026-22162 4.6

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain an incomplete fix for CVE-2025-53928, where a Remote Code Execution vulnerability still exists in the MCP node of the workflow engine. MaxKB only restricts the referencing code path (loading MCP config from the database). The else branch, responsible for loading mcp_servers directly from user-supplied JSON remains completely unpatched. Since mcp_source is an optional field (required=False), an attacker can simply omit it or set it to any non-referencing value to bypass the fix. By calling the workflow creation API directly with a crafted JSON payload, an attacker can inject a complete MCP node configuration with stdio transport, arbitrary command, and args — achieving RCE when the workflow is triggered via chat. This issue has been fixed in version 2.8.0.

Record
EUVD-2026-22162
CVSS 3.1
4.6 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L
Updated
2026-11-02
NVD 4.6

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain an incomplete fix for CVE-2025-53928, where a Remote Code Execution vulnerability still exists in the MCP node of the workflow engine. MaxKB only restricts the referencing code path (loading MCP config from the database). The else branch, responsible for loading mcp_servers directly from user-supplied JSON remains completely unpatched. Since mcp_source is an optional field (required=False), an attacker can simply omit it or set it to any non-referencing value to bypass the fix. By calling the workflow creation API directly with a crafted JSON payload, an attacker can inject a complete MCP node configuration with stdio transport, arbitrary command, and args — achieving RCE when the workflow is triggered via chat. This issue has been fixed in version 2.8.0.

Record
CVE-2026-39417
CVSS 3.1
4.6 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L
CVSS 3.1
5.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L
Weakness
CWE-20, CWE-78
Updated
2026-11-02
OSV 4.6

MaxKB: RCE via MCP stdio command injection in workflow engine

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain an incomplete fix for CVE-2025-53928, where a Remote Code Execution vulnerability still exists in the MCP node of the workflow engine. MaxKB only restricts the referencing code path (loading MCP config from the database). The else branch, responsible for loading mcp_servers directly from user-supplied JSON remains completely unpatched. Since mcp_source is an optional field (required=False), an attacker can simply omit it or set it to any non-referencing value to bypass the fix. By calling the workflow creation API directly with a crafted JSON payload, an attacker can inject a complete MCP node configuration with stdio transport, arbitrary command, and args — achieving RCE when the workflow is triggered via chat. This issue has been fixed in version 2.8.0.

Record
CVE-2026-39417
CVSS 3.1
4.6 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:L
Weakness
CWE-20, CWE-78
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-39417 is a medium vulnerability (CVSS 4.6) in 1panel-dev Maxkb, published April 14, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.24%, the 15th percentile. No source names a fixed version.

References

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