# CVE-2026-49353: 9Router: Local-Only Access Gate Bypass in 9router via Host Header SpoofING

> Attackers can bypass local-only access controls via Host header spoofing in reverse proxy setups to execute code through MCP child processes.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Jul 2026
- **Updated:** 16 Jul 2026
- **Also known as:** GHSA-6g2f-w7g3-77vf

## What is CVE-2026-49353?

CVE-2026-49353 is a high-severity authentication bypass vulnerability in decolua 9router, published on 15 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-290 (Authentication Bypass by Spoofing)

## Which versions are affected by CVE-2026-49353?

2 open source packages ship an affected version, including 9router.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `9router` | npm | All versions to 0.4.55 | None |
| `9router` | npm | All versions to 0.4.55 | None |

## How do I fix CVE-2026-49353?

No fix has been published for CVE-2026-49353 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-49353 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49353 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49353 and fix it if it is affected.

What it is: CVE-2026-49353 is a high-severity authentication bypass vulnerability in decolua 9router, published on 15 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49353 exists.

Affected packages and fixed versions:
- 9router (npm): affected all versions up to 0.4.55; no fix listed
- 9router (npm): affected all versions up to 0.4.55; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-49353/ (Markdown: https://insights.sbomify.com/CVE-2026-49353/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49353
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49353
- OSV: https://osv.dev/vulnerability/CVE-2026-49353

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49353/
Summaries are generated and may contain mistakes; the official description above is the record.