# CVE-2026-26483: Mettle SendPortal stored XSS in template management

Source: https://junglewise.ai/threats/cve-2026-26483-mettle-sendportal-stored-xss-in-template-management  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-20. Updated: 2026-07-20  
License: CC BY 4.0 with a link back

CVE-2026-26483 · Severity: info · CVSS 0 · Published 2026-07-20

Mettle SendPortal, an open-source email marketing platform, contains a security flaw in its template management system. An attacker with access to create or edit email templates can inject malicious scripts that will run in the browsers of other users who view those templates. This could lead to unauthorized access to user accounts, theft of session information, or the performance of actions on behalf of other administrators.

Technologies: [Mettle Sendportal](https://junglewise.ai/threats/technologies/sendportal). Vendors: [Mettle](https://junglewise.ai/threats/vendors/mettle).

## Quick answers

**Is CVE-2026-26483 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-26483 being exploited in the wild.

**How severe is CVE-2026-26483?** Informational severity, with a CVSS score of 0, published 20 July 2026.

**Which products and versions are affected?** Mettle Sendportal 3.0.1 and earlier.

**Is there a fix for CVE-2026-26483?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-26483 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-26483?** Check whether you run Mettle Sendportal 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 Mettle SendPortal versions 3.0.1 and earlier. The vulnerability is located in the template management functionality, specifically within the 'content' parameter of the /templates endpoint. The application fails to properly sanitize user-supplied input or encode output when rendering these templates. An authenticated attacker can inject arbitrary JavaScript code that is persistently stored on the server. When other users (such as administrators) view the affected template, the malicious script executes in their browser context, potentially allowing for session hijacking or privilege escalation.

## Affected products

- Mettle SendPortal 3.0.1 and earlier

## Timeline

- 2026-06-22: disclosed: Initial discovery and Gist publication
- 2026-07-20: advisory: CVE published to NVD

## References

- [https://gist.github.com/WinBlah12/8dbc1eae788945c6ea6ab1a2cdfd7cb1](https://gist.github.com/WinBlah12/8dbc1eae788945c6ea6ab1a2cdfd7cb1)
- [https://github.com/mettle/sendportal](https://github.com/mettle/sendportal)

## Related threats

- [Mettle SendPortal missing authentication in APIv1 Webhooks](https://junglewise.ai/threats/cve-2026-15192-mettle-sendportal-missing-authentication-in-apiv1-webhooks)
- [Mettle SendPortal authorization bypass in Campaign Creation Endpoint](https://junglewise.ai/threats/cve-2026-15191-mettle-sendportal-authorization-bypass-in-campaign-creation)
- [Mettle Sendportal stored XSS in Campaign webview](https://junglewise.ai/threats/cve-2026-10234-mettle-sendportal-stored-xss-in-campaign-webview)