Executive Summary

CVE-2026-42890 is a vulnerability in the Actual macOS desktop application (versions before 26.5.0) that uses Electron 39.2.7. The issue arises because the ELECTRON_RUN_AS_NODE fuse is not disabled, which allows an attacker who can place a file on disk or control command-line arguments to run the Actual.app binary with the environment variable ELECTRON_RUN_AS_NODE=1 set.

This causes the application to behave like a Node.js REPL (Read-Eval-Print Loop), enabling the attacker to execute arbitrary code with the same entitlements and code signature as the application. This bypasses macOS Gatekeeper security checks, effectively allowing signed-binary abuse.

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Impact Analysis

This vulnerability allows an attacker with local access to execute arbitrary code within the context of the Actual application, inheriting its entitlements and code signature.

• The attacker can access network, file system, keychain, and automation features available to the app.
• It bypasses macOS Gatekeeper, which normally restricts untrusted code execution.

However, exploitation requires local access with low complexity and no user interaction, and it does not directly impact the overall confidentiality, integrity, or availability of the system.

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Detection Guidance

This vulnerability can be detected by checking if the Actual macOS application (version prior to 26.5.0) is present and if the ELECTRON_RUN_AS_NODE environment variable can be set or is set when invoking the Actual.app binary. Since exploitation requires local access and the ability to place files or control command-line arguments, detection involves verifying the application version and monitoring for suspicious invocation of the Actual.app binary with ELECTRON_RUN_AS_NODE=1.

Suggested commands to detect the vulnerability include:

• Check the installed Actual app version: `mdls -name kMDItemVersion /Applications/Actual.app`
• Search for processes running Actual.app with the ELECTRON_RUN_AS_NODE environment variable set: `ps aux | grep Actual` and inspect environment variables if possible.
• Check for suspicious invocations or scripts that set ELECTRON_RUN_AS_NODE=1 when launching Actual.app.

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Mitigation Strategies

The immediate mitigation step is to upgrade the Actual macOS application to version 26.5.0 or later, where the vulnerability has been patched by disabling the ELECTRON_RUN_AS_NODE fuse.

Additionally, restrict local access to the system to prevent attackers from placing files or controlling command-line arguments that could exploit this vulnerability.

Monitor and audit the usage of the Actual.app binary to detect any unauthorized or suspicious executions with the ELECTRON_RUN_AS_NODE environment variable.

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Compliance Impact

The vulnerability allows an attacker with local access to execute arbitrary code with the application's privileges, including access to network, file system, keychain, and automation features.

However, the CVE description and resources do not explicitly mention any direct impact on compliance with common standards and regulations such as GDPR or HIPAA.

Since the vulnerability enables code execution with the app's entitlements, it could potentially lead to unauthorized access to sensitive data, which might have implications for regulatory compliance depending on the data handled by the application.

No specific statements about compliance impact are provided in the available information.

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