CVE-2025-1087: Kong Insomnia RCE Vulnerability

CVE-2025-1087 Overview

Kong Insomnia Desktop Application before version 11.0.2 contains a template injection vulnerability that allows attackers to execute arbitrary code. The vulnerability exists due to insufficient validation of user-supplied input when processing template strings, which can lead to arbitrary JavaScript execution in the context of the application.

Critical Impact

This template injection vulnerability enables remote attackers to achieve arbitrary code execution through malicious template strings, potentially compromising developer workstations and sensitive API credentials stored within Insomnia.

Affected Products

• Kong Insomnia Desktop Application versions prior to 11.0.2

Discovery Timeline

• 2025-05-09 - CVE-2025-1087 published to NVD
• 2025-09-17 - Last updated in NVD database

Technical Details for CVE-2025-1087

Vulnerability Analysis

This vulnerability is classified as CWE-20 (Improper Input Validation) and represents a template injection flaw in the Kong Insomnia API client. The application processes user-supplied template strings without adequate sanitization, allowing malicious actors to inject and execute arbitrary JavaScript code within the Electron-based desktop application context.

Insomnia is a popular API development platform used by developers to design, debug, and test APIs. The application supports dynamic templating features that allow users to insert variables and expressions into requests. However, the template parsing engine fails to properly validate input, creating an exploitation vector that can be triggered through crafted API project files or shared workspaces.

The network-based attack vector combined with the requirement for user interaction (opening a malicious project file) makes this vulnerability particularly dangerous in collaborative development environments where teams share Insomnia workspaces.

Root Cause

The root cause of CVE-2025-1087 lies in improper input validation within the template processing functionality. When Insomnia parses template strings embedded in API requests, environment variables, or workspace configurations, it fails to adequately sanitize user-controlled input before evaluation. This allows attackers to craft malicious template expressions that break out of the intended templating context and execute arbitrary JavaScript code within the Node.js/Electron runtime environment.

Attack Vector

The attack can be conducted remotely over a network by convincing a victim to open a malicious Insomnia project file or import a compromised workspace. The exploitation requires user interaction—the victim must actively open or import the attacker-controlled content. Once triggered, the injected template code executes with the same privileges as the Insomnia application, potentially allowing attackers to:

• Access sensitive API keys and authentication tokens stored in the application
• Read and exfiltrate local files accessible to the application process
• Execute system commands through Node.js child processes
• Pivot to other systems using compromised credentials

The vulnerability mechanism involves crafting template expressions that escape the intended variable substitution context. For detailed technical analysis of the exploitation technique, refer to the TantoSec Blog Post.

Detection Methods for CVE-2025-1087

Indicators of Compromise

• Unusual Insomnia workspace files received from untrusted sources containing complex or obfuscated template expressions
• Unexpected outbound network connections from the Insomnia process
• Child processes spawned by Insomnia that are not typical of normal application behavior
• Access to sensitive files or environment variables outside normal API testing workflows

Detection Strategies

• Monitor for Insomnia application processes spawning unexpected child processes or shell commands
• Implement endpoint detection rules to identify JavaScript code execution patterns within Electron applications
• Review imported workspace files for suspicious template syntax before opening in the application
• Use application-level sandboxing to detect and block anomalous file system or network access from Insomnia

Monitoring Recommendations

• Enable verbose logging for Insomnia application activities on developer workstations
• Deploy endpoint detection and response (EDR) solutions capable of monitoring Electron-based application behavior
• Implement network monitoring to detect unusual outbound connections from developer tools
• Establish baseline behavior profiles for API development tools to identify anomalous activities

How to Mitigate CVE-2025-1087

Immediate Actions Required

• Upgrade Kong Insomnia Desktop Application to version 11.0.2 or later immediately
• Avoid opening Insomnia workspace files or project exports from untrusted or unknown sources
• Review recently imported workspaces for suspicious template expressions or unexpected configurations
• Consider temporarily using web-based API testing tools until the patched version is deployed

Patch Information

Kong has addressed this vulnerability in Insomnia version 11.0.2. Organizations should prioritize upgrading all instances of the Insomnia Desktop Application to this version or later. The fix implements proper input validation and sanitization for template string processing, preventing the injection of arbitrary code through template expressions.

For the latest release information and download links, refer to the GitHub Insomnia Repository.

Workarounds

• Restrict the use of template features in Insomnia until the patched version can be deployed
• Implement strict workspace import policies, only allowing files from trusted sources
• Run Insomnia in isolated environments or containers to limit the impact of potential code execution
• Use application sandboxing solutions to restrict file system and network access for the Insomnia process