CVE-2026-81919

Concrete CMS below 9.5.3 is vulnerable to Cross-Site Request Forgery (CSRF) in Block Arrangement Endpoint

Concrete CMS below 9.5.3 did not validate an anti-CSRF token on the block-arrangement backend endpoint (the arrange() action of Concrete\Controller\Backend\Page\ArrangeBlocks). The action enforced page-edit authorization but performed no token check, and its route accepted any HTTP method, so an attacker could induce a signed-in content editor into loading an attacker-controlled page that auto-submitted a cross-site request and reordered or moved blocks in the draft version of a page the victim was permitted to edit. The default null cookie SameSite configuration let the victim's session cookie accompany the forged request. The Concrete CMS security team gave this vulnerability a CVSS v4.0 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 from Tenzai for reporting.

CVSS 4.0 · 2.3 Low EPSS < 1% KEV · Not listed

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CVE-2026-81916

Incorrect Authorization in the Concrete CMS Express Entries Dashboard below version 9.5.3 Allows Entry Creation in an Unauthorized Object

Concrete CMS before 9.5.3 evaluated the authorization check for an Express entry submission against the entity of the posted form rather than the entity identified by the dashboard route. As a result, a user permitted to add entries to one Express object could create entries in a different Express object outside their authorization scope, potentially polluting protected datasets, triggering workflows, or injecting content into administrative processes. The dashboard submit route resolved the mutated entity from the attacker-controlled route ID while the permission check validated the independently posted form's entity, and the submission proceeded because the two entities were never compared. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.1 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed

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CVE-2026-81917

Concrete CMS below 9.5.3 is vulnerable to Stored XSS in the Document Library block file description and tags

Concrete CMS below 9.5.3 does not apply HTML output escaping to the file description and tags fields when rendering the Document Library block, so a user with permission to edit file properties could store a script payload that executed in the browser of any visitor to a page displaying the block with the description or tags column enabled, including unauthenticated visitors. Successful exploitation could allow theft of session data or actions performed in the visitor's context. The block controller returned the description and tags values without the h() escaping already applied to the title column, and the block view template wrote the returned value directly into the results table The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N. Thanks Nguyen Manh Thuan for reporting.

CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed

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CVE-2026-81927

Concrete CMS before 9.5.3 is vulnerable to Stored XSS via SVG upload in "Reject" sanitization mode

Concrete CMS before 9.5.3 contained a stored cross-site scripting vulnerability in SVG file handling. When SVG processing was set to the non-default "Reject files containing potentially harmful elements" mode (concrete.file_manager.images.svg_sanitization.action = reject), uploaded SVGs were checked only against a small built-in blocklist covering the script element and on* event-handler attributes; the broader enshrined/svg-sanitize pass still ran, but its result was discarded, so vectors it would have stripped, such as a javascript: URI in an xlink:href, were stored unmodified and executed when the file was opened directly. A user able to upload files could thereby run arbitrary JavaScript in the browser of any user who viewed the file. The default sanitize mode was not affected. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 1.8 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Oriol Ortiz for reporting.

CVSS 4.0 · 1.8 Low EPSS < 1% KEV · Not listed

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Concrete Cms

CVE-2026-81918

Concrete CMS below 9.5.3 is vulnerable to Stored XSS via the Date Format field in the Page Attribute Display block

Concrete CMS below 9.5.3 is vulnerable to Stored XSS via the Date Format field in the Page Attribute Display block. A user with edit_page_contents permissions could store a payload which executes in the browser of any visitor who viewed a page where the block was configured to display a date-type attribute. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 4.8 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Oriol Ortiz for reporting.

CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed

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CVE-2026-81900

Concrete CMS before 9.5.3 is vulnerable to Stored XSS in the YouTube block (vWidth/vHeight)

Concrete CMS before 9.5.3 applied only trim() to the YouTube block's stored width and height values and printed them into iframe HTML attributes without escaping or integer casting, resulting in stored cross-site scripting. A user with edit_block permission could inject an event handler that executed script for visitors rendering the page, acting with administrative privileges where the victim was an administrator. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks sh4d0byss for reporting.

CVSS 4.0 · 7.3 High EPSS < 1% KEV · Not listed

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CVE-2026-81910

Concrete CMS 9 through 9.5.2 is vulnerable to Server-Side Template Injection (SSTI) in Theme Customizer via Unvalidated Style Values

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.

CVSS 4.0 · 5.9 Medium EPSS < 1% KEV · Not listed

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Concrete Cms

CVE-2026-68529

Concrete CMS 9.0.0 through 9.5.2 us missing authorization in the Express entries advanced-search dashboard action allowing a low-privileged user to read other entities' Express entries

Concrete CMS 9.0.0 through 9.5.2 was missing an authorization check on the Express entries advanced-search dashboard action. The advanced_search() method in DashboardSelectableExpressEntryListTrait resolved an Express entity directly from a user-supplied entity ID and rendered that entity's entries without invoking canViewExpressEntries(), the per-entity permission check that the sibling results() action enforced. An authenticated dashboard user holding view_express_entries on a single Express entity could read the entries of any other entity, including secret attribute values, by requesting the advanced-search action with that entity's ID, disclosing form submissions and CRM-style records across the per-entity permission boundary that Express is designed to enforce. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

CVSS 4.0 · 2.1 Low EPSS < 1% KEV · Not listed

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Concrete Cms

CVE-2026-18421

Concrete CMS 9.0.0-9.5.2 Boards data source dashboard is missing an authorization check, allowing a low-privileged board editor to modify or delete configured data sources on boards they do not control

Concrete CMS 9 through 9.5.2 does not perform an authorization check in three actions of the Boards data source dashboard controller (update, update_data_source, and delete_data_source), which resolve a ConfiguredDataSource directly from an attacker-supplied identifier without confirming the requester's edit permission on the owning board. A user granted edit_board_settings on a single board was therefore able to modify or permanently delete the configured data sources of any other board on the site, halting the affected board's content feed and resetting its custom weighting. The CSRF token that guards these actions was validated but bound to the action name rather than to the target object, so a token legitimately obtained for one board could be replayed against another board's ConfiguredDataSource identifier and did not constrain access. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

CVSS 4.0 · 2.1 Low EPSS < 1% KEV · Not listed

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CVE-2026-68531

Concrete CMS below 9.5.3 is vulnerable to Authenticated Denial of Service via Unescaped SQL LIKE Wildcards in Keyword Search

Concrete CMS 9 before 9.5.3 did not escape SQL LIKE wildcard characters in the keyword search filters used by the file manager, file folders, and page list, allowing an authenticated user with editor-level or higher privileges to submit a crafted search containing many single-character wildcards. Because the keyword input was placed into the LIKE clause without neutralizing its wildcard metacharacters, a short request could force the database to evaluate every row and perform a full-table scan, and repeated or wildcard-dense searches could sustain elevated database CPU and I/O, degrading responsiveness for other users on large installations. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N. Thanks noivan for reporting.

CVSS 4.0 · 2.1 Low EPSS < 1% KEV · Not listed

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Concrete Cms

CVE-2026-68530

Concrete CMS 9.0.0 through 9.5.2 is Missing Authorization on Board Instance Actions Allowed a Board Editor to Access and Delete Other Boards' Instances

Concrete CMS 9 through 9.5.2 did not perform an authorization check on several board-instance actions in the Boards area of the Dashboard. The instance details single-page controller resolved a board instance directly from an attacker-supplied instance ID and then viewed, refreshed, regenerated, or deleted it without verifying that the requester held edit_board_settings on the instance's parent board. As a result, a user granted board-edit rights on a single board could reach the instances of any other board on the site by supplying their instance IDs. The affected actions bypassed the controller's permission-checked accessor (the same accessor used by the read view, which runs canEditBoardSettings on the parent board) and validated only an action-scoped CSRF token, which is bound to the action name rather than to the target object and is therefore reusable across boards. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

CVSS 4.0 · 2.1 Low EPSS < 1% KEV · Not listed

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CVE-2026-81899

Concrete CMS 9.0 to 9.5.2 is vulnerable to Stored XSS via group folder name on the Members > Groups dashboard

Concrete CMS 9.0.0 to 9.5.2 stored group folder names without sanitization and printed them unescaped on the Members > Groups dashboard page, resulting in stored cross-site scripting. The add and edit group-folder handlers stored the submitted folder name without neutralizing HTML, and the group search grid returned it without output encoding, so the Groups dashboard rendered the name as live markup. An authenticated user holding the Add Group Folder permission could store a script payload as a folder name that executed in the session of any administrator who viewed the Groups dashboard, enabling session and token theft and any action available in the administrator's context. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Lý Chấn Hưng (hunglyvn) for reporting.

CVSS 4.0 · 7.3 High EPSS < 1% KEV · Not listed

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Concrete Cms

CVE-2026-68534

Concrete CMS below 9.5.2 is vulnerable to Stored XSS via unescaped Express entry labels in association selectors

Concrete CMS before 9.5.3 rendered Express entry labels as raw HTML when displaying associated entries, resulting in stored cross-site scripting. An unauthenticated attacker could submit a payload through a public Express Form; it then executed in an administrator's dashboard session when the associated entry was viewed, or in the browser of any visitor to a page using an Express Entry List block with association columns, allowing actions to be performed with that user's privileges. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks v01demort for reporting.

CVSS 4.0 · 2.3 Low EPSS < 1% KEV · Not listed

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CVE-2026-68533

Missing Authorization in Concrete CMS versions below 9.5.3 Conversation File Upload Allows File Import Without the Add Message Attachments Permission

Concrete CMS below 9.5.3 conversation attachment uploaded endpoint imported files into the file manager before evaluating the "Add Message Attachments" permission, which was only checked after the file had been stored. A user denied that permission, or an unauthenticated visitor on a guest-posting configuration, could import approved files of allowed types into the file manager. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

CVSS 4.0 · 2.3 Low EPSS < 1% KEV · Not listed

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Concrete Cms

CVE-2026-18115

In Concrete CMS 9.2.0 to 9.5.2, Missing Authorization in REST API Users update() and change_password Enables Account Takeover.

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.

CVSS 4.0 · 7.4 High EPSS < 1% KEV · Not listed

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CVE-2026-18122

Concrete CMS 9.2.0 to 9.5.2 Express REST API list endpoint exposes restricted Express entries via Missing Authorization

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.

CVSS 4.0 · 6 Medium EPSS < 1% KEV · Not listed

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Concrete Cms

CVE-2026-81909

Concrete CMS 9 through 9.5.2 is vulnerable to Missing Authorization in the orphaned-block alias route, allowing an authenticated editor to disclose and force-delete arbitrary blocks

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.

CVSS 4.0 · 5.9 Medium EPSS < 1% KEV · Not listed

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Concrete Cms

CVE-2026-81908

Missing Authorization in Concrete CMS 9.2.0 to 9.5.2 REST API Groups List Endpoint Allows Authenticated Users to Enumerate All Groups

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.

CVSS 4.0 · 6 Medium EPSS < 1% KEV · Not listed

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Concrete Cms

CVE-2026-68528

Concrete CMS 9.5.2 and below is vulnerable to Stored XSS in RSS Displayer Block via Unescaped Remote Feed Item title

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.

CVSS 4.0 · 6 Medium EPSS < 1% KEV · Not listed

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Concretecms

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Concrete Cms

CVE-2026-7888

Concrete CMS below 9.5.3 is vulnerable to PHP Object Injection via unserialize() calls in the Workflow, Form block, and File/Set components that lack the allowed_classes restriction.

Concrete CMS below 9.5.3 is vulnerable to PHP Object Injection via unserialize() calls in the Workflow, Form block, and File/Set components that lack the allowed_classes restriction. The Form block and File/Set sinks were addressed in 9.5.2; the Workflow component sinks were addressed in 9.5.3. An unauthenticated attacker may trigger arbitrary PHP object instantiation if a malicious serialized payload has been placed in the database. Thanks XananasX7 and Sanjorn Keeratirungsan (dizconnect) for independently reporting the original components, and sh4d0byss for reporting the Workflow component wasn't fixed in 9.5.2. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 8.4 with vector CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/ VC:H/VI:H/VA:H/SC:N/SI:N/SA:N.

CVSS 4.0 · 8.4 High EPSS < 1% KEV · Not listed

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Concrete Cms