# CVE-2026-111048: FOSSBilling: Low-privileged staff can run JavaScript in administrators' browsers via stored XSS in support ticket notes

Status: published. Published: 2026-11-02. Updated: 2026-11-02.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- FOSSBilling / FOSSBilling: >= 0.1.0, < 0.8.9 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 4.0: 8.4 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-79

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-493h-fvcx-6q62 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/FOSSBilling/FOSSBilling/pull/4548 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/FOSSBilling/FOSSBilling/commit/87528920b6cb1ba6f113583253eb4d7abdd1d8c6 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.9 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-111048; retrieved 2026-11-02; source updated 2026-11-02

Revision: f5aac81581e8da7698626f6657c31fa6d75db8b83989c5650eb34c45def43950

Canonical: https://y2.dev/cve/CVE-2026-111048

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