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[ CVE-2026-56681 · Published 22 Sep 2026 ]

9Router has an Authentication Bypass in Public LLM API via Spoofable X-9r-Real-Ip Header

CVSS 7.3 EPSS <1%Fix available

[ Why it matters ]Priority signals

  • Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

9Router is an AI router & token saver. Prior to 0.5.6, 9Router deployments that allow requests to reach Next.js without the sanitizing custom-server.js wrapper trust the client-supplied X-9r-Real-Ip header in src/dashboardGuard.js when isLocalRequest decides whether canAccessPublicLlmApi may skip API-key validation for /api/v1/* routes. A remote unauthenticated attacker can set X-9r-Real-Ip to 127.0.0.1 and be classified as a local client, including on the verified GET /api/v1/models route. This permits unauthorized use of the instance owner's configured LLM providers, consumption of paid credits, and enumeration of configured providers and models. This issue is fixed in version 0.5.6.

[ Fixes ]Fixes and patches

  • 9router 0.5.8Fixed version · GitHub Advisories · npm package 9router: upgrade to 0.5.8 or later (affected <= 0.5.4)

[ Packages ]Affected open-source packages

[ References ]References