A stored cross-site scripting (XSS) vulnerability exists in osTicket 1.18.3 due to improper sanitization of the thread entry title field. User-controlled input in the title is stored without adequate HTML escaping and later rendered in multiple staff-facing templates without proper output encoding. An attacker can inject arbitrary JavaScript by submitting a crafted ticket reply or email with a malicious subject line.
https://github.com/osTicket/osTicket/commit/1e39bf1cf78fa298285f19b98f6a6dbb6808de19
https://github.com/osTicket/osTicket/blob/v1.18.3/include/staff/templates/thread-entry.tmpl.php#L84
https://github.com/osTicket/osTicket/blob/v1.18.3/include/staff/templates/thread-entries.tmpl.php
https://github.com/osTicket/osTicket/blob/v1.18.3/include/staff/templates/reply-expand.tmpl.php
https://github.com/fr3akhacks/cve-disclosures/blob/master/osTicket/CVE-2026-38446.md