MISP Core contained broken access-control checks in the bulk deletion flows for Event Reports and Sharing Groups. The affected deleteSelection handlers authorized deletion using broad role-level permissions instead of validating authorization for each selected object. For Event Reports, EventReportsController::deleteSelection relied on the global perm_add capability rather than a per-report ownership/authorization check. As a result, a contributor-level user could submit report IDs or UUIDs for reports belonging to other organisations and hard-delete them instance-wide. The fix changed the callback to call EventReport::fetchIfAuthorized($user, $itemId, 'delete') for each selected report before deletion. For Sharing Groups, SharingGroupsController::deleteSelection relied on the global perm_sharing_group capability rather than verifying ownership of each selected sharing group. This allowed a sharing-group-capable user to hard-delete sharing groups owned by other organisations, bypassing the per-object ownership gate used by the single-object delete action. The fix changed the callback to call SharingGroup::checkIfOwner($user, $itemId) for each selected sharing group. An authenticated attacker with the relevant broad role permission could abuse the affected bulk deletion endpoints to delete objects outside their organisation’s authorization scope, causing loss of event-report content or sharing-group configuration across the instance.

MISP core contained multiple broken access-control flaws where authorization checks were performed against the wrong entity, or where ownership/editability checks were missing on write paths. In affected subsystems, a lower-privileged authenticated user with the relevant feature permission could cause the application to authorize one object but mutate another, or could modify objects that were merely visible rather than editable by the user’s organization. The affected paths included: * Event Reports tag removal: the route-authorized report could differ from the report ID used for tag detachment, enabling cross-organization tag removal from another event report * Collection Elements bulk deletion: bulk deletion authorized against a collection whose ID matched the collection-element row ID, rather than the element’s actual parent collection, enabling deletion of elements from collections the user did not own. * Analyst Data capture/update: nested analyst data updates could overwrite an existing record without applying the normal canEditAnalystData ownership check, enabling cross-organization overwrite of analyst data records. * Template Elements editing: editing authorized against a template whose ID matched the template-element ID, rather than the element’s actual parent template, enabling unauthorized edits to another organization’s template elements. * Decaying Model editing and mappings: write paths loaded models using view-scope access but did not verify edit ownership, enabling users to edit or remap visible models owned by another organization.  Successful exploitation could allow an authenticated user with subsystem-specific permissions to perform unauthorized cross-organization modifications or deletions of MISP data, resulting in integrity loss, unauthorized tampering with shared intelligence, and disruption of analyst workflows.

A vulnerability was identified in the ShadowAttribute proposal creation workflow. The add action accepted user-controlled ShadowAttribute request data without removing the id field before saving the record. Because the underlying framework treats a supplied primary key as an instruction to update an existing record, an authenticated user able to submit shadow attribute proposals could provide the identifier of an existing ShadowAttribute and cause that record to be updated instead of creating a new proposal. This can result in unauthorized modification of existing shadow attributes, potentially affecting proposals associated with events the user should not be able to alter. Depending on deployment configuration and accessible API responses, the issue may also expose or move proposal data across event contexts. The vulnerability is caused by trusting a client-supplied primary key during object creation. The fix removes the id field from incoming ShadowAttribute data before processing, ensuring that the endpoint always creates a new proposal rather than updating an existing one. This has been fixed in MISP 2.5.38.

MISP contained multiple mass assignment vulnerabilities in the handling of collections, tag collections, event delegations, and shadow attributes. Several controller actions accepted user-supplied fields that should have remained server-controlled, including record identifiers and ownership-related fields such as id, org_id, orgc_id, and user_id. An authenticated attacker with access to the affected endpoints could craft requests containing protected fields in order to alter object ownership, redirect an update to another record, overwrite existing event delegation requests, or modify shadow attribute proposals belonging to another organization. This could result in unauthorized modification of MISP objects and, depending on object visibility and sharing configuration, unauthorized access to or transfer of sensitive threat intelligence data. The issue was fixed by explicitly pinning ownership and identity fields to their stored values during edit operations and by removing user-supplied primary keys from create-only save paths. Affected components: * CollectionsController::edit() * EventDelegationsController::delegateEvent() * ShadowAttributesController::edit() * TagCollectionsController::edit()915 * TagCollectionsController::editWithTags() Attack requirements: The attacker must be authenticated and able to reach the affected MISP endpoints. No user interaction is required.

A mass assignment vulnerability exists in MISP’s sharing group creation endpoint. When creating a new sharing group, the controller did not remove a user-supplied id field before saving the submitted data. In CakePHP, supplying a primary key in the save data can cause a create() followed by save() operation to update an existing record instead of creating a new one. An authenticated user with permission to add sharing groups could therefore submit the identifier of an existing sharing group and modify that sharing group without passing the normal edit access-control checks. This may allow the attacker to take over or alter sharing groups they do not otherwise have access to, potentially affecting the confidentiality and integrity of information shared through those groups. Affected component: app/Controller/SharingGroupsController.php, add() action

An improper authorization vulnerability in MISP allowed an authenticated organization administrator to access or modify user settings belonging to site administrator accounts within the same organization. The affected access-control checks scoped administrative actions by organization membership but did not exclude higher-privileged site administrator users. As a result, an organization administrator could potentially view or alter site administrator user settings and related login profile information, crossing the intended privilege boundary between organization administration and site-wide administration. The patch hardens the ACL logic by excluding site administrator accounts from organization administrator–managed user sets, adding explicit authorization failure when a target user is not administrable, and ensuring user setting and login profile operations fail closed.