Jan Local API Server CORS Origin Reflection via 0.0.0.0 Binding
Published Jul 24, 2026
5.3
MEDIUMCVSS 4.0
EPSS 0.33%
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.
Affected products
-
- Version 0StatusaffectedConstraints<=0.8.4
- Version
-
- Version StatusunaffectedConstraints-
- Version
No data.
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
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
1 other source (NVD) ▾
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
PoCAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed Jul 24, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 4, 2026.
Score over time
Jul-Oct 2026- EPSS v5
Percentile over time
- EPSS v5
Table of values (2 key points)
Flat stretches are collapsed. Showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 4, 2026 | 0.33% (0.00331) | 23.91th | v5 (v2026.06.15) |
| Jul 25, 2026 | 0.19% (0.00187) | 8.55th | v5 (v2026.06.15) |
References (4)
- https://github.com/janhq/jan/commit/3e1c1e724f696620d89bb4a9cc18a380e0753757 patch
- https://github.com/janhq/jan/issues/8453 technical-descriptionexploitissue-tracking
- https://github.com/janhq/jan/pull/8506 issue-trackingpatch
- https://www.vulncheck.com/advisories/jan-local-api-server-cors-origin-reflection-via-binding third-party-advisory
| Link | Providers | Tags |
|---|---|---|
| https://github.com/janhq/jan/commit/3e1c1e724f696620d89bb4a9cc18a380e0753757 | patch | |
| https://github.com/janhq/jan/issues/8453 | technical-descriptionexploitissue-tracking | |
| https://github.com/janhq/jan/pull/8506 | issue-trackingpatch | |
| https://www.vulncheck.com/advisories/jan-local-api-server-cors-origin-reflection-via-binding | third-party-advisory |
Change history (0)
No recorded changes yet.