CVE-2026-56681 json
9Router: Authentication Bypass in Public LLM API via Spoofable X-9r-Real-Ip Header
published last mo. modified last mo. also GHSA-5mj8-gf6m-fhw8 , EUVD-2026-84541
- cvss
- 7.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.1%
- EPSS 1.1% chance of exploitation in 30 days, percentile 66%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- npm 9router 0.5.8
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Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- last mo.
Exploit prediction
1.11% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-11).
Exploits and checks
- github.com https://github.com/decolua/9router/security/advisories/GHSA-5mj8-gf6m-fhw8 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L |
| GitHub | 3.1 | 7.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | 9router | <0.5.8 |
0.5.8 |
Affected products
- decolua 9router
Classification
- Weakness
-
- CWE-807 Reliance on Untrusted Inputs in a Security Decision
References
Sources
- CVE List CVE-2026-56681
- GitHub Advisory GHSA-5mj8-gf6m-fhw8
- NVD CVE-2026-56681
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