EUVD-2026-52403
GHSA-w47h-2qx7-7rfr
Severity by source
AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Ticket submission is unauthenticated by default (PR:N); a staff member must view the thread to trigger execution (UI:R); payload fires in the privileged staff portal context, changing scope (S:C).
Primary rating from Vendor (mitre).
CVSS VectorVendor: mitre
Lifecycle Timeline
3DescriptionCVE.org
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.
AnalysisAI
Stored XSS in osTicket 1.18.3 allows an unauthenticated external attacker to inject arbitrary JavaScript through the ticket thread entry title field, with the payload executing in the staff portal whenever a support agent views the affected thread. Source code references confirm that at least four PHP templates echo $entry->title without calling the existing Format::htmlchars() sanitization helper, a straightforward omission patched in commit 1e39bf1. A public researcher disclosure (fr3akhacks/cve-disclosures) confirms proof-of-concept details are available, though SSVC rates exploitation status as none and no CISA KEV listing has been issued, indicating no confirmed active exploitation at time of analysis.
Technical ContextAI
osTicket is a PHP-based open-source help desk ticketing platform. The root cause is CWE-79 (Improper Neutralization of Input During Web Page Generation): user-controlled ticket subject/title data is persisted to the database and later rendered in multiple server-side PHP templates using bare echo $entry->title statements, bypassing the application's own Format::htmlchars() HTML-encoding helper. The commit diff confirms four affected files: include/staff/templates/thread-entry.tmpl.php (line 82), include/client/templates/thread-entry.tmpl.php (line 38), include/client/templates/thread-export.tmpl.php (line 44), and include/staff/templates/thread-entries-preview.tmpl.php. The CVSS Scope:Changed metric reflects that the payload executes in the elevated-privilege staff portal context, distinct from the unauthenticated submitter context. The CPE string in the intelligence data (cpe:2.3:a:n/a:n/a:*) is non-specific and unusable for asset correlation; affected product identity is derived from the CVE description and v1.18.3 GitHub source references.
RemediationAI
Apply the upstream fix from commit 1e39bf1cf78fa298285f19b98f6a6dbb6808de19 in the osTicket GitHub repository (https://github.com/osTicket/osTicket/commit/1e39bf1cf78fa298285f19b98f6a6dbb6808de19), which wraps all unescaped $entry->title output with Format::htmlchars() across the four affected templates. Upstream fix available via commit; a patched tagged release version newer than 1.18.3 has not been independently confirmed at time of analysis - monitor the osTicket releases page for a version incorporating this commit before deploying in production. As an interim compensating control, restrict access to the osTicket staff portal to internal networks or VPN, which eliminates the staff-side XSS execution surface for external attackers even if the injection point remains open; this trades off remote staff access convenience. Additionally, deploying a Content Security Policy header (e.g., script-src 'self') on the osTicket domain can significantly limit the impact of any stored XSS payloads by blocking inline script execution, though CSP integration in a legacy PHP application requires regression testing to avoid breaking legitimate portal functionality.
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Same weakness CWE-79 – Cross-site Scripting (XSS)
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External POC / Exploit Code
Leaving vuln.today