Executive brief
osTicket is an open-source customer support ticket system. A security flaw allows an attacker to trick a staff member's browser into performing unauthorized actions, such as deleting notes or tickets, simply by having the staff member view a malicious ticket or image. This could lead to unauthorized data modification or loss of administrative records.
Technical details
A Cross-Site Request Forgery (CSRF) vulnerability exists in osTicket up to version 1.18.3 due to a bypass in the Dispatcher component. The file 'include/class.dispatcher.php' incorrectly allows HTTP method overrides via the '_method' parameter in GET requests. Because the application's CSRF protection only validates POST requests, an attacker can use GET-based vectors (such as <img> tags) to trigger state-changing actions (e.g., DELETE or POST) that would normally require a CSRF token. An attacker can exploit this by embedding a malicious URL in a ticket that, when viewed by an authenticated agent, executes administrative actions in the agent's context. A pull request has been submitted to restrict method overrides to POST data, but a formal patch has not yet been merged.
Affected products
- osTicket osTicket up to 1.18.3
Timeline
- 2026-04-11: disclosed: Pull request with fix submitted to the project repository
- 2026-05-09: advisory: Vulnerability published via VulDB/NVD