Auth bypass in Onyx-Dot-App Onyx

CVE-2026-63178

Onyx is an open-source AI platform. Prior to 4.3.0, Onyx Enterprise Edition's PATCH /manage/admin/user-group/{user_group_id} and POST /manage/admin/user-group/{user_group_id}/add-users endpoints in ee/onyx/server/user_group/api.py call update_user_group and add_users_to_user_group in ee/onyx/db/user_group.py without enforcing _validate_curator_can_modify_group, allowing a curator to add accounts to arbitrary groups and obtain document access through get_acl_for_user and the OpenSearch access_control_list filter. This issue is fixed in version 4.3.0.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.005 (41.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 42nd percentile — 41.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-63178: held from 0.003 to 0.005.

EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-63178?
CVE-2026-63178 is a medium-severity vulnerability in Onyx-Dot-App Onyx, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2026-08-17.
How severe is CVE-2026-63178?
Medium severity. CVSS v3 base score is 6.5 out of 10.