CVE-2026-42853: ApostropheCMS CLI Command Injection Vulnerability

Technical summary

The @apostrophecms/cli package versions ≤3.6.0 fail to sanitize user input from the password prompt in the `apos create` command before passing it to a shell execution function. This CWE-78 (OS Command Injection) flaw means an attacker can embed shell metacharacters or command sequences into the password field, which are then executed with the privileges of the user running the CLI tool. The vulnerability sits at the intersection of insufficient input validation and unsafe command construction.

Business impact

Organizations relying on ApostropheCMS for content management face a risk of unauthorized command execution if a privileged user is tricked or coerced into entering a malicious string during site creation. This could lead to data exfiltration, lateral movement within the development or hosting environment, or disruption of service deployments. The impact is most acute in environments where developers share systems or where access controls are weak.

Affected systems

The vulnerability affects all installations of the @apostrophecms/cli package version 3.6.0 and earlier. It is triggered only when users invoke the `apos create` command interactively. ApostropheCMS is a Node.js-based CMS typically deployed in development and production environments; this flaw impacts CLI tool usage across Windows, macOS, and Linux systems where Node.js is available.

Exploitability

Exploitation requires an attacker to already possess local system access and sufficient privileges to interact with the CLI tool (administrative user execution context). The attack also requires user interaction—specifically, the attacker must convince or trick the administrator into running the vulnerable command and entering a crafted password string. While the barrier to initial access is high, the actual exploitation is trivial once those conditions are met, making this a concern primarily in supply-chain or insider-threat scenarios.

Remediation

Until a patched version is released by the ApostropheCMS project, mitigation relies on operational controls: restrict CLI tool usage to trusted, isolated systems; limit who can execute `apos create` via file system permissions; use environment-based configuration instead of interactive prompts where possible; and monitor command-line activity for suspicious shell metacharacters. Organizations should monitor the official ApostropheCMS repositories and security advisories for a patched release and apply it immediately upon availability.

Patch guidance

As of the vulnerability publication date (2026-06-12), no patched versions of the @apostrophecms/cli package have been released. Verify the latest available version on npm (npmjs.com/package/@apostrophecms/cli) and the official ApostropheCMS GitHub repository for any security updates. Once a patch is available, update the package via `npm install @apostrophecms/cli@latest` or the version number specified in the vendor advisory, then verify the fix by reviewing the commit history or release notes for the injection-handling changes.

Detection guidance

Monitor systems running ApostropheCMS CLI for: (1) execution of the `apos create` command, particularly with unusual password input patterns containing shell metacharacters like backticks, dollar signs, semicolons, or pipes; (2) unexpected child process spawning or system command execution immediately following CLI invocation; (3) audit logs showing administrative users running CLI commands during off-hours or from unusual accounts. Log aggregation and process execution monitoring tools (e.g., osquery, Sysmon, or cloud-native equivalents) are valuable for detection.

Why prioritize this

Although this is a CVSS 6.5 MEDIUM vulnerability, it warrants prioritization because: (1) it enables arbitrary code execution, the highest-impact security outcome; (2) it affects a development tool that may be central to your deployment pipeline; (3) a malicious or compromised developer with CLI access poses a significant supply-chain risk; and (4) the lack of a patched version means the window for exploitation remains open indefinitely until one is published. Prioritize inventory and access control over patching urgency until a fix is available.

Risk score, explained

CVSS 3.1 score of 6.5 (MEDIUM) reflects: Attack Vector Local (the attacker must be on the system), Attack Complexity Low (no special conditions needed once they are local), Privileges Required High (must be an admin-level user), User Interaction Required (someone must trigger the `apos create` command), and Confidentiality, Integrity, and Availability impacts all High (arbitrary code execution). The score appropriately penalizes the local-only and high-privilege requirements, but acknowledges that code execution, once achieved, is unrestricted.

Frequently asked questions