Concretecms vulnerabilities

Concrete CMS versions 9.5.0 through 9.5.2 are vulnerable to Open Redirect via the rcURL parameter. An attacker can craft a single link on the site's own domain that sends a user to an arbitrary external site immediately after authentication, facilitating phishing and credential theft. The same handling is present in the registration flow, giving a second entry point on sites with registration enabled. Concrete CMS versions prior to 9.5.0 do not include the rcURL parameter or this allowlist and are not affected. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Michal M. for reporting.

Concrete CMS before 9.5.3 is vulnerable to Cross-Site Request Forgery in the Move Multiple Groups feature. The dashboard/users/groups/bulkupdate/confirm() endpoint moved the selected group tree nodes without validating an action token, so a state-changing group move could be processed for an authenticated user who did not initiate it. Because relocating a group under a new parent causes that group's members to inherit the parent's permissions, a forged move can change effective authorization. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.7 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

Concrete CMS versions 9.0.0 to 9.5.2 is vulnerable to Stored XSS in Board Custom Slot dialog. The custom_slot save_template endpoint authorizes the request only against the target board instance (canEditBoardContents()) and then persists the client-supplied selectedTemplateOption[collection] verbatim, rather than rebuilding the content object collection server-side and verifying that each item belongs to the authorized board's data pool. A user with permission to edit the contents of at least one board instance can therefore store a forged summary object whose description field carries a JavaScript-bearing HTML payload. The default summary template renders the description field without output encoding, so the payload executes in the browser of any user who views the affected board slot, including anonymous front-end visitors and dashboard users who preview the resulting rule or block. This can enable session or action takeover and escalation toward an administrator. Concrete CMS versions below 9 do not include the Boards feature and are not affected. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.8 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

Concrete CMS before 9.5.3 did not validate an anti-CSRF token in the Calendar event duplicate dialog controller (concrete/controllers/dialog/event/duplicate.php) submit() action, which duplicated a calendar event after checking only canAccess() and the per-resource canAddCalendarEvent() permission, so a crafted cross-site request could cause an authenticated user with add-event permission to create duplicate CalendarEvents and CalendarEventVersions records under their own authority. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Concrete CMS 9 through 9.5.2 is vulnerable to Server-Side Template Injection (SSTI) in Theme Customizer via Unvalidated Style Values. Values submitted through the customizer (color channels and other style properties handled by ColorStyle and sibling Style classes such as FontFamilyStyle and ImageStyle) are interpolated into server-compiled LESS source without neutralization of LESS syntax, allowing a user with the Theme Customization permission to inject arbitrary LESS directives. By injecting the @import (inline) directive, an attacker can read arbitrary files on the server and reach internal network resources through PHP stream wrappers. The compiled output, including any disclosed file contents, is written to the site's publicly served CSS cache, exposing database credentials, private keys, and other application secrets, and enabling server-side request forgery. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.9 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

Concrete CMS 9 through 9.5.2 is vulnerable to Missing Authorization in the block alias route (Process::alias() in concrete/controllers/backend/block/process.php).It does not verify that the referenced block is genuinely orphaned on the target page, nor that the caller holds any permission over the source block. A user granted only an area-scoped add_block_to_area delegation on their own page can therefore pass any block ID on the site: the source block's content is duplicated into an area the rogue editor controls, disclosing that content, and the original block is then force-deleted in the same request, destroying arbitrary site content. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.9 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

Concrete CMS 9.2.0 to 9.5.2 contain a missing authorization vulnerability in the REST API Groups list endpoint. The listGroups() method in concrete/src/Api/Controller/Groups.php registers a permissions checker callback that unconditionally returns true, so no per-object (tree node) authorization is enforced when the group collection is returned. An authenticated user whose API token carries the groups:read scope can call GET /ccm/api/1.0/groups and receive every group on the site regardless of the view permissions on those groups, disclosing the organization's group structure, roles, and access hierarchy. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Concrete CMS RSS Displayer block below version 9.5.3 rendered remote feed item titles without HTML escaping, resulting in stored cross-site scripting. An attacker able to control a title in a syndicated feed could execute script in the site origin for any visitor to the affected page, including administrators, without holding an account on that site. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.0 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

Concrete CMS 9.2.0 to 9.5.2 Express REST API list endpoint exposes restricted Express entries via Missing Authorization; the Concrete CMS REST API's Express entry collection endpoint disabled the per-entry view permission check. An OAuth token with read scope for an Express entity could enumerate entries that its user context lacked permission to view, disclosing each entry's public identifier, URL, label, dates, and any attribute or associated-entry data requested via the includes parameter. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

Concrete CMS OAuth callback login path prior to version 9.5.3 did not check whether an account was active or email-validated before establishing a session. A deactivated or unvalidated user with an existing OAuth binding could complete authentication and receive a session that was fully authenticated for the callback response, with the login recorded and login events dispatched. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

Concrete CMS below 9.5.3 stores user validation hashes for multiple purposes (email/registration validation, password reset, and persistent login) in a single table with a type column, but the redemption path resolves a hash by value alone and does not verify its type. As a result, a hash issued for one purpose can be redeemed for another: a long-lived registration hash (60-day expiry) can be submitted to the password-change endpoint to set a new password on the target account, and a password-reset hash can be submitted to the email-validation endpoint to activate an account. Exploitation requires the attacker to first obtain a valid hash through a separate channel (for example email interception, log exposure, or SSRF against an internal mail relay), so the flaw amplifies the impact of any hash disclosure rather than creating a standalone entry point. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

Concrete CMS 9.5.2 and below is vulnerable to an authorization bypass (IDOR) because the frontend calendar lightbox endpoint (/ccm/calendar/view_event/{bID}/{occurrence_id}) does not verify that the caller is permitted to view the calendar that owns the requested event occurrence. The controller loads the occurrence directly from an attacker‑supplied, sequential identifier without confirming that it belongs to the calendar configured on the referenced block. An unauthenticated visitor who can render any public calendar block with lightbox properties enabled could therefore supply an arbitrary occurrence identifier and disclose event metadata — title, date, description, page link, and configured event attributes — from calendars they are not permitted to view. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

Concrete CMS 9 through 9.5.2 did not validate an anti-CSRF token in the Boards custom slot dialog controller (concrete/controllers/dialog/board/custom_slot.php) saveTemplate() action. The action created a board_slot_proxy Block and dispatched an AddCustomSlotToBoardCommand against a board instance while gating only on the per-resource canEditBoardContents() permission, so a crafted cross-site request could cause a user holding board-edit permission with an active session to write attacker-chosen slot and template data to a board under their own authority. The state-changing database write completed before any downstream rendering, so the forged request succeeded even when the HTTP response returned a non-200 status. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Concrete CMS versions 8.3.0 through 9.5.2 are vulnerable to an authorization bypass in the Calendar event edit dialog (concrete/controllers/dialog/event/edit.php). The dialog checked permissions against the calendar identifier supplied in the request rather than the calendar owning the targeted event occurrence. A user with the "Add Event" permission on a single calendar could read and overwrite events on calendars they were not permitted to access, and could delete an event's original local occurrence. Publishing the injected version to the live calendar, which demotes the previously approved version, additionally required the actor's approve_calendar_event workflow rights or an auto-approving workflow. The Concrete CMS Security Team gave this a rank of 5.9 with CVSS 4.0 vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Concrete CMS below 9.5.3 registered view assets for every sub-block of a Stack, Container, or layout area without checking whether the requesting user could view that sub-block. An unauthenticated visitor could recover configuration values emitted by a restricted sub-block's asset registration — such as a site's configured Google Maps API key — from any public page embedding an affected Stack, Container, or layout area, despite the block-level permission restriction. Any sub-block type whose asset or header hooks output configuration values is affected.  The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori (Tenzai) for reporting.

Concrete CMS version 9.0 to 9.5.0 is vulnerable to Stored XSS via page name in the Atomik theme. A rogue editor can inject arbitrary JavaScript that executes in the context of any authenticated user visiting the affected account pages. This can lead to session hijacking, credential theft, malicious actions performed on behalf of users, and potential privilege escalation. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori (Tenzai) for reporting.

Concrete CMS 9.5.0 and below is vulnerable to IDOR + wrong-authorization-level in the Express association Reorder dialog.  This can cause Cross-entity state tampering with view-only permission on one entry. To be affected, a website has to be using express and relying on express entity ordering. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Concrete CMS 9.5.0 and below is vulnerable to CSRF via Backend\File::approveVersion. Victim with edit_file_contents permission is CSRF'd into publishing an attacker-chosen previously-uploaded version (downgrade to an older version of a file, or activation of a co-editor's unpublished version). The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file approveVersion(). The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori (Tenzai) for reporting.