Auth bypass in Concrete Cms

CVE-2026-18115

Concrete CMS 9.2.0 to 9.5.2 did not enforce per-field edit_user_properties permissions on the REST API user write endpoints (PUT /ccm/api/1.0/users/{uID} and POST /ccm/api/1.0/users/{uID}/change_password). A user with an update-scoped OAuth token and permission to edit only one non-sensitive field could change another non-superuser's password, username, email, and attributes, taking over that account. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.4 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

Vulnerability class: Broken Access Control

Published · last modified .

EPSS exploit prediction

EPSS: 0.004 (38.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 38.2% 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-2026-18115: held from 0.003 to 0.004.

EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.002

Affected products

Weakness classification (CWE)

References