CVE-2026-49353

Deferred Deferred - Pending Action

Remote Proxy Bypass in 9Router via Header Spoofing

Publication date: 2026-07-15

Last updated on: 2026-07-16

Assigner: GitHub, Inc.

Description

9Router is an AI router & token saver. In 0.4.45 and earlier, 9Router's src/dashboardGuard.js local-only access gate used Host and Origin headers in isLocalRequest() to protect /api/mcp/*, /api/tunnel/*, and /api/cli-tools/*, allowing header spoofing in reverse proxy or tunnel deployments to reach MCP child process stdin paths.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-07-15

Last Modified

2026-07-16

Generated

2026-08-05

AI Q&A

2026-07-16

EPSS Evaluated

2026-08-03

NVD

CVE-2026-49353

Affected Vendors & Products

Vendor	Product	Version / Range
9router	9router	0.4.45

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-290	This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.

Attack-Flow Graph

Executive Summary

The vulnerability in 9Router versions 0.4.45 and earlier involves improper access control in the src/dashboardGuard.js file. The isLocalRequest() function uses Host and Origin headers to restrict access to sensitive API endpoints like /api/mcp/*, /api/tunnel/*, and /api/cli-tools/*. However, these headers can be spoofed in reverse proxy or tunnel deployments, allowing unauthorized access to MCP child process stdin paths.

Detection Guidance

This vulnerability involves header spoofing in 9Router's local-only access gate. To detect it, inspect network traffic for requests to /api/mcp/*, /api/tunnel/*, or /api/cli-tools/* with suspicious Host or Origin headers. Check if reverse proxy or tunnel deployments allow header modifications that bypass local access restrictions.

Impact Analysis

This vulnerability could allow attackers to bypass local-only access restrictions and interact with sensitive APIs. If exploited, it may lead to unauthorized access to system commands, data exfiltration, or further compromise of the router's MCP child processes, potentially affecting network security and privacy.

Compliance Impact

The vulnerability allows header spoofing in reverse proxy or tunnel deployments, potentially enabling unauthorized access to sensitive API endpoints like /api/mcp/*, /api/tunnel/*, and /api/cli-tools/*. This could lead to data breaches or unauthorized data processing, which may violate GDPR's data protection requirements and HIPAA's safeguards for protected health information.

Mitigation Strategies

Upgrade 9Router to a version newer than 0.4.45 where the issue is fixed. If upgrading is not possible, disable access to /api/mcp/*, /api/tunnel/*, and /api/cli-tools/* endpoints or implement strict Host and Origin header validation at the reverse proxy or tunnel level.

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