Description
osTicket v1.18.3 is vulnerable to Stored Cross-Site Scripting (XSS) via the email From-header display name. The value is extracted without sanitization in include/class.mailparse.php and stored raw in the poster field of ost_thread_entry. When an unauthenticated attacker sends a reply email to an existing ticket from an unregistered address with an XSS payload in the From display name.
References3
Metrics
- CVSS 3.1
-
6.1
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - EPSS — exploit probability
- 0% percentile: 30 · as of 13 November 2026
- CWE
- CWE-79
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.