CVE-2026-42277: Onyx: IDOR in /chat/file/{file_id} allows any authenticated user to download other users files

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-08 · updated 2026-06-17
Weakness: CWE-639

Description

Onyx is an open-source AI platform. Prior to versions 3.0.9, 3.1.6, and 3.2.6, the GET /chat/file/{file_id} endpoint allows any authenticated user to download any other user's uploaded files by providing the file UUID. The endpoint verifies the caller is authenticated but never checks that the file belongs to them. An attacker who knows or obtains a file UUID can access confidential documents, chat attachments, and other files uploaded by any user in the system. This issue has been patched in versions 3.0.9, 3.1.6, and 3.2.6.

Affected products

onyx-dot-app onyx: before 3.0.9; from 3.1.0 before 3.1.6; from 3.2.0 before 3.2.6 — fixed in 3.0.9, 3.1.6, 3.2.6

How to fix

Upgrade to a fixed version: onyx-dot-app onyx 3.0.9, 3.1.6, 3.2.6. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-42277 or the next vulnerability affects your stack