HIGH 8.2 GitHub
CVE-2026-55641
9router: Unauthenticated `/v1` proxy access via `Host`-header spoofing → open AI relay + SSRF
## Summary
9router's request guard decides a request is "local" (and therefore exempt from API-key auth on the `/v1` LLM proxy) by reading the **client-controlled `Host` header**. Because 9router binds `0.0.0.0` by default (and the CLI misleadingly prints "localhost"), a remote, unauthenticated attacker who can reach the port can send `Host: localhost` to be treated as local and obtain `/v1` proxy access with **no API key, no CLI token, and no dashboard login**. In the default configuration (`r
Affected Products
- npm/9router < 0.5.2
References
- https://github.com/advisories/GHSA-86m2-fcxq-5q7c
- https://github.com/decolua/9router/security/advisories/GHSA-86m2-fcxq-5q7c
- https://nvd.nist.gov/vuln/detail/CVE-2026-55641
- https://github.com/decolua/9router/commit/b282f0554972ea35281520738759d76abcd0b0b3
This high severity vulnerability with a CVSS score of 8.2 was published on 2026-08-28 via GitHub. Affected: npm/9router < 0.5.2.
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