CVE-2026-56681
HighPublic exploit9Router: Authentication Bypass in Public LLM API via Spoofable X-9r-Real-Ip Header
Published Sep 22, 2026 · Updated Sep 30, 2026 · Also known as EUVD-2026-84541, GHSA-5mj8-gf6m-fhw8
Key Facts
Patch immediately- CVE-2026-56681 is a high-severity vulnerability (CVSS 7.3 v3.1) affecting 9router (npm).
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 1.0% probability of exploitation in the next 30 days.
- Fixed versions are available, including 9router 0.5.6, 9router 0.5.8.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
CVSS v3.1
7.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
EPSS (30-day exploit likelihood)
1.0%
Higher than 61.1% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-56681 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| 9routernpm | >= < 0.5.6 | 0.5.8 |
Patched Releases
9router
0.5.6, 0.5.8
Timeline
Publicly disclosed
Sep 22, 2026
Last updated
Sep 30, 2026
Weakness Type
- CWE-807 Reliance on Untrusted Inputs in a Security Decision
References
- advisoryGHSA advisory
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56681.json
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-56681
- otherhttps://github.com/decolua/9router
- otherhttps://github.com/decolua/9router/commit/efd20be8d81ef2e256a7037f3aa78e6b567b5fd3
FAQ
Common Questions.
9Router is an AI router & token saver.
Affected: 9router (npm) versions >= < 0.5.6. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including 9router 0.5.6, 9router 0.5.8.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Is CVE-2026-56681 Running On Your Attack Surface?
Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.
Request A Demo