msgbyte Tianji up to 1.31.28 Template Processing template.ts formatString information disclosure

Summaryinfo

A vulnerability marked as problematic has been reported in msgbyte Tianji up to 1.31.28. The affected element is the function formatString of the file src/server/utils/template.ts of the component Template Processing. The manipulation leads to information disclosure. This vulnerability is uniquely identified as CVE-2026-55240. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in msgbyte Tianji up to 1.31.28. It has been rated as problematic. This issue affects the function formatString of the file src/server/utils/template.ts of the component Template Processing. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. The summary by CVE is:

Tianji is an open source analytics, uptime monitoring, and server status platform. Prior to 1.31.29, formatString() in src/server/utils/template.ts passes survey feedTemplate and monitor notification templates to lodash template(), while the default evaluate pattern remains enabled. A workspace administrator can store an evaluate block using the <% code %> form, and the public survey.submit endpoint renders a survey template when an unauthenticated user submits a response. The compiled template executes server-side JavaScript in the Tianji Node.js process, allowing command execution, secret disclosure, data modification, or service disruption. This issue is fixed in version 1.31.29.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-55240 since 06/16/2026. The exploitation is known to be easy. The attack may be initiated remotely. Additional levels of successful authentication are required for exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1592 according to MITRE ATT&CK.

Upgrading to version 1.31.29 eliminates this vulnerability.

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Productinfo

Vendor

• msgbyte

Name

• Tianji

Version

• 1.31.0
• 1.31.1
• 1.31.2
• 1.31.3
• 1.31.4
• 1.31.5
• 1.31.6
• 1.31.7
• 1.31.8
• 1.31.9
• 1.31.10
• 1.31.11
• 1.31.12
• 1.31.13
• 1.31.14
• 1.31.15
• 1.31.16
• 1.31.17
• 1.31.18
• 1.31.19
• 1.31.20
• 1.31.21
• 1.31.22
• 1.31.23
• 1.31.24
• 1.31.25
• 1.31.26
• 1.31.27
• 1.31.28

Website

• Product: https://github.com/msgbyte/tianji/

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