CVE-2026-18115 Missing authorization in Concrete CMS
Attackers with limited OAuth tokens can bypass field-level permissions to change other users' credentials, leading to account takeover.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-18115?
CVE-2026-18115 is a high-severity missing authorization vulnerability in Concrete CMS, published on 15 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
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.
Weakness: CWE-862
Which versions are affected by CVE-2026-18115?
How do I fix CVE-2026-18115?
No fix has been published for CVE-2026-18115 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-18115 being exploited?
There is no known exploitation of CVE-2026-18115 in the wild and no public exploit code.
Sources
Also known as GHSA-j7cg-26vv-9hjf.