FOSSBilling is an open source billing and client-management platform. From 0.1.0 until 0.8.9, the admin/support/note_create endpoint stores the note parameter without sanitization in the support_ticket_note table, and src/modules/Support/templates/admin/mod_support_tickets.html.twig renders each stored support ticket note through innerHTML in the admin ticket list. A staff user with only the support.manage_tickets permission can store HTML or JavaScript that executes when another staff member opens the ticket notes. The script runs with the viewing staff member's session and privileges, can read a CSRF token and accessible client or invoice data, and can perform administrative actions available to the viewer, including a Super Administrator. The ticket detail page is not affected because its Twig rendering uses autoescaping. This issue is fixed in version 0.8.9.
0.3% estimated probability of exploitation activity in the next 30 days; 20th percentile. Scored 2026-11-04. A forecast for this CVE across the internet, not for your own systems.
CISA's assessment (SSVC)
Exploitation: none · Automatable: no · Technical impact: total, assessed 2026-11-03. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
CWE
CWE-79Improper Neutralization of Input During Web Page Generation (Cross-site Scripting)
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Versions
From the CNA's record in the CVE List.
Product
Affected
FOSSBilling
>= 0.1.0, < 0.8.9
Attack patterns (CAPEC)
CAPEC-63 Cross-Site Scripting (XSS) Likelihood: High · Severity: Very High
CAPEC-85 AJAX Footprinting Likelihood: High · Severity: Low
CAPEC-209 XSS Using MIME Type Mismatch Severity: Medium
CAPEC-588 DOM-Based XSS Likelihood: High · Severity: Very High
CAPEC-591 Reflected XSS Likelihood: High · Severity: Very High
CAPEC-592 Stored XSS Likelihood: High · Severity: Very High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.