Vulnerability in Janhq Jan
CVE-2026-66005
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.003 (25.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Janhq Jan — versions 0, 3e1c1e724f696620d89bb4a9cc18a380e0753757
Weakness classification (CWE)
References
- github.com/janhq/jan/commit/3e1c1e724f696620d89bb4a9cc18a380e0753757 (patch)
- github.com/janhq/jan/issues/8453 (issue-tracking, technical-description, exploit)
- github.com/janhq/jan/pull/8506 (issue-tracking, patch)
- www.vulncheck.com/advisories/jan-local-api-server-cors-origin-reflection-via-bi… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-66005?
- CVE-2026-66005 is a medium-severity vulnerability in Janhq Jan, classified under CWE-183. CVSS score: 6.3/10. Published 2026-07-24.
- How severe is CVE-2026-66005?
- Medium severity. CVSS v3 base score is 6.3 out of 10.