MCP Context Forge: RestrictedPython sandbox bypass via getattr builtin in python_sandbox_server

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-53710
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-15 17:17:19 UTC
Updated2026-09-15 20:17:17 UTC
DescriptionMCP Context Forge is an AI gateway, registry, and proxy for MCP, A2A, REST, and gRPC APIs. Prior to 1.0.2, the python_sandbox_server in mcp-servers/python/python_sandbox_server/src/python_sandbox_server/server_fastmcp.py exposes raw getattr through safe_builtins, omits a required _getattr_ guard, and relies on validate_code checks for literal dangerous dunder strings. An attacker can construct dunder names at runtime, traverse the Python class hierarchy, reach subprocess.Popen, and execute OS commands with the server process privileges through the execute_code MCP tool. The HTTP/SSE transport can expose this tool without authentication, while stdio-only deployments have reduced network reachability. The issue affects the python_sandbox_server subproject and does not directly affect the core Context Forge gateway or proxy components. This issue is fixed in version 1.0.2.

Risk And Classification

Primary CVSS: v3.1 10 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Problem Types: CWE-94 | CWE-693 | CWE-94 CWE-94: Improper Control of Generation of Code ('Code Injection') | CWE-693 CWE-693: Protection Mechanism Failure

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
3.1CNADECLARED10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA IBM Mcp-context-forge affected < 1.0.2 Not specified

References

ReferenceSourceLinkTags
github.com/IBM/mcp-context-forge/releases/tag/v1.0.2 [email protected] github.com
github.com/IBM/mcp-context-forge/security/advisories/GHSA-xm98-3vcf-fph7 [email protected] github.com
github.com/IBM/mcp-context-forge/commit/63a2900e6301b9c8a483a38d3737a1be... [email protected] github.com
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