# CVE-2026-53641: FOSSBilling stored XSS in client email history views

Source: https://junglewise.ai/threats/cve-2026-53641-fossbilling-stored-xss-in-client-email-history-views  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-06. Updated: 2026-07-06  
License: CC BY 4.0 with a link back

CVE-2026-53641 · Severity: info · CVSS 4.8 · Published 2026-07-06

FOSSBilling is an open-source platform used by businesses to manage client billing and support. A security flaw allows an administrator to embed malicious code into emails sent to customers. When a customer views their email history in the client portal, this code could execute in their browser, potentially allowing the attacker to steal session information or perform unauthorized actions on the customer's behalf.

Technologies: [FOSSBilling](https://junglewise.ai/threats/technologies/fossbilling). Vendors: [FOSSBilling](https://junglewise.ai/threats/vendors/fossbilling).

## Quick answers

**Is CVE-2026-53641 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-53641 being exploited in the wild.

**How severe is CVE-2026-53641?** Informational severity, with a CVSS score of 4.8, published 6 July 2026.

**Which products and versions are affected?** FOSSBilling >= 0.6.0, <= 0.7.2.

**Is there a fix for CVE-2026-53641?** A patch was published on 2026-08-01: Fixed in version 0.8.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-53641 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-53641?** Check whether you run FOSSBilling at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A stored cross-site scripting (XSS) vulnerability exists in FOSSBilling's email history modules (mod_email_index.html.twig and mod_email_email.html.twig). The root cause is the use of the Twig '|raw' filter when rendering 'content_html' inside a JavaScript template literal for an iframe's 'srcdoc' attribute, which bypasses output escaping. An attacker with administrative access can inject payloads using backticks, template expressions (${...}), or script tags to break out of the JavaScript context. Successful exploitation allows for session cookie theft, CSRF token disclosure, or unauthorized actions in the context of the victim client. The issue is resolved in version 0.8.0.

## Affected products

- FOSSBilling FOSSBilling >= 0.6.0, <= 0.7.2

## Timeline

- 2026-06-12: advisory: GitHub Security Advisory published
- 2026-07-06: disclosed: CVE published to NVD
- 2026-08-01: patched: Fixed in version 0.8.0

## References

- [https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-q6c8-6r72-35f7](https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-q6c8-6r72-35f7)

## Related threats

- [FOSSBilling stored XSS in support ticket notes](https://junglewise.ai/threats/cve-2026-111048-fossbilling-is-an-open-source-billing-and-client-management)
- [FOSSBilling CSRF vulnerability in staff guest login endpoint](https://junglewise.ai/threats/cve-2026-112374-fossbilling-before-0-8-9-contains-a-cross-site-request-forgery)
- [FOSSBilling email enumeration via guest signup endpoint](https://junglewise.ai/threats/cve-2026-111056-fossbilling-is-an-open-source-billing-and-client-management)
- [FOSSBilling path traversal in template_exists endpoint](https://junglewise.ai/threats/cve-2026-111053-fossbilling-is-an-open-source-billing-and-client-management)
- [FOSSBilling authorization bypass in extension configuration management](https://junglewise.ai/threats/cve-2026-111046-fossbilling-is-an-open-source-billing-and-client-management)