Kanboard through 1.2.52, fixed in commit 564cc30, BoardAjaxController save() method (used by the kanban board drag-and-drop endpoint) validates the caller's role on the attacker-supplied project_id but never verifies that the supplied task_id actually belongs to that project. Because task identifiers are sequential integers shared across the entire instance, any authenticated user who is a member of at least one project can enumerate and move (corrupt/hide) tasks belonging to any other project on the same instance, including private projects they have no membership or role on.
https://github.com/kanboard/kanboard/pull/5853
https://github.com/kanboard/kanboard/issues/5852
https://github.com/kanboard/kanboard/commit/564cc30e1e360959572e01e158734d9475c05903
Published: 2026-07-15
Updated: 2026-07-15
Base Score: 8.5
Vector: CVSS2#AV:N/AC:L/Au:S/C:N/I:C/A:C
Severity: High
Base Score: 8.1
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Severity: High
Base Score: 7.2
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00355