CVE-2026-77339

Process Compose: Browser DNS rebinding lets websites control local process-compose MCP tools

Published Sep 18, 2026 CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
Description
Process Compose is a scheduler and orchestrator for non-containerized applications. Prior to 1.120.0, the MCP SSE listener in src/mcp/server.go accepts browser-origin requests to /sse and the returned message endpoint without validating the Host header, validating the Origin header, or authenticating the caller. When MCP SSE is enabled, a malicious website can use DNS rebinding to reach the loopback listener and issue MCP requests. If expose_control_tools is enabled, the attacker can enumerate process state, read or search logs, truncate logs, and start, stop, restart, or scale local processes; configured user-defined tools can expose additional commands and output. The Gin REST API token middleware does not protect this separately started MCP listener. This issue is fixed in version 1.120.0.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-5gm3-9crp-6g3v Process Compose: Browser DNS rebinding lets websites control local process-compose MCP tools
History
Type Values Removed Values Added
First Time appeared F1bonacc1
F1bonacc1 process-compose
Vendors & Products F1bonacc1
F1bonacc1 process-compose
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Process Compose is a scheduler and orchestrator for non-containerized applications. Prior to 1.120.0, the MCP SSE listener in src/mcp/server.go accepts browser-origin requests to /sse and the returned message endpoint without validating the Host header, validating the Origin header, or authenticating the caller. When MCP SSE is enabled, a malicious website can use DNS rebinding to reach the loopback listener and issue MCP requests. If expose_control_tools is enabled, the attacker can enumerate process state, read or search logs, truncate logs, and start, stop, restart, or scale local processes; configured user-defined tools can expose additional commands and output. The Gin REST API token middleware does not protect this separately started MCP listener. This issue is fixed in version 1.120.0.
Title Process Compose: Browser DNS rebinding lets websites control local process-compose MCP tools
Weaknesses CWE-306
CWE-346
References
Metrics cvssV4_0

{'score': 5.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:H/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 18, 2026, 4:49 PM
Reserved
Aug 20, 2026, 7:24 PM
Status
Deferred
Published
Sep 18, 2026, 5:17 PM
Modified
Sep 24, 2026, 9:25 PM