# Uptime Kuma Server-side Template Injection in notification templates

Source: https://junglewise.ai/threats/uptime-kuma-server-side-template-injection-in-notification-templates-8547405a  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-10-20. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

Severity: low · CVSS 3.1 · Published 2025-10-20

Uptime Kuma is a self-hosted monitoring tool used to track the availability of websites and services. A Server-side Template Injection vulnerability in notification templates allows authenticated users to read arbitrary files from the server, potentially exposing sensitive configuration files, secrets, or data stored on the system.

Technologies: [uptime-kuma (npm)](https://junglewise.ai/threats/technologies/uptime-kuma). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Low severity, with a CVSS score of 3.1, published 20 October 2025.

**Which products and versions are affected?** Louis Lam Uptime Kuma 1.23.0 through 1.23.16, 2.0.0-beta.4 and earlier.

**Is there a fix for This vulnerability?** A patch was published on 2025-10-20: Patched in versions 1.23.17 and 2.0.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is This vulnerability attacked?** It is attacked over the network.

**Am I affected?** Check whether you run uptime-kuma (npm). 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

The vulnerability is a Server-side Template Injection (SSTI) in Uptime Kuma's renderTemplate() function, which instantiates a Liquid template engine and processes user-controlled input without sanitization or sandboxing. In notification types such as Webhook and Telegram, user-editable fields are passed directly to renderTemplate(), allowing attackers to inject malicious Liquid template syntax (e.g., {% render '/etc/passwd' %}). An authenticated user with notification configuration permissions can craft a custom webhook body containing template injection payloads to read arbitrary files from the server. The attack requires authentication but no further user interaction. Patches are available in versions 1.23.17 and 2.0.0.

## Affected products

- Louis Lam Uptime Kuma 1.23.0 through 1.23.16, 2.0.0-beta.4 and earlier

## Timeline

- 2025-10-20: disclosed
- 2025-10-20: patched: Patched in versions 1.23.17 and 2.0.0

## References

- [https://github.com/louislam/uptime-kuma/security/advisories/GHSA-vffh-c9pq-4crh](https://github.com/louislam/uptime-kuma/security/advisories/GHSA-vffh-c9pq-4crh)
- [https://github.com/louislam/uptime-kuma](https://github.com/louislam/uptime-kuma)

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- [Uptime Kuma ReDoS in notification provider configuration](https://junglewise.ai/threats/uptime-kuma-redos-in-notification-provider-configuration-e7e79209)
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