---
id: CVE-2026-66005
title: >-
  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-…
summary: >-
  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-…
severity: medium
cvss: 6.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L'
cwe:
  - CWE-183
  - CWE-942
vendor: janhq
product: jan
affected:
  - jan <= 0.8.4
published: '2026-07-24'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T18:17:02.120'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-66005'
references:
  - url: >-
      https://github.com/janhq/jan/commit/3e1c1e724f696620d89bb4a9cc18a380e0753757
    label: disclosure@vulncheck.com
  - url: 'https://github.com/janhq/jan/issues/8453'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/janhq/jan/pull/8506'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/jan-local-api-server-cors-origin-reflection-via-binding
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-07-24T15:32:21.328068Z'
epss: 0.00198
epssPercentile: 0.09839
ingestedAt: '2026-09-17T18:25:15.980Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.