CVE-2026-66005

medium

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.

References

https://www.vulncheck.com/advisories/jan-local-api-server-cors-origin-reflection-via-binding

https://github.com/janhq/jan/pull/8506

https://github.com/janhq/jan/issues/8453

https://github.com/janhq/jan/commit/3e1c1e724f696620d89bb4a9cc18a380e0753757

Details

Source: Mitre, NVD

Published: 2026-07-24

Updated: 2026-07-24

Risk Information

CVSS v2

Base Score: 7.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

Severity: High

CVSS v3

Base Score: 6.3

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L

Severity: Medium

CVSS v4

Base Score: 5.3

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

Severity: Medium