CVE-2026-15187: Prototype Pollution in Enquirer ≤2.4.1 – Patch Guidance

Technical summary

CVE-2026-15187 is a prototype pollution vulnerability in the enquirer package (up to version 2.4.1) within the Enquirer.set function of the Public Package API. The vulnerability stems from improper sanitization of the question.name argument, allowing an attacker with existing authentication credentials to inject properties into Object.prototype. This is classified under CWE-1321 (Improper Restriction of Rendered UI Layers or Frames) and CWE-94 (Improper Control of Generation of Code ('Code Injection')). The attack surface is network-accessible, requires low complexity, and mandates prior authentication. The CVSS 3.1 score is 4.3 (MEDIUM severity) with a vector of CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N, indicating integrity impact but no confidentiality or availability consequences.

Business impact

Organizations running enquirer-dependent applications face limited but real risk. The integrity impact allows authenticated users to modify application behavior in unexpected ways—for example, altering form validation logic or triggering unintended code paths. While this is not a direct data breach or system outage vector, it can erode application trustworthiness and create opportunities for privilege abuse or data manipulation if chained with other weaknesses. Teams managing developer tools and CLI utilities that depend on enquirer should prioritize remediation to prevent supply-chain compromise scenarios.

Affected systems

The vulnerability affects enquirer package versions up to and including 2.4.1. Any application directly using the Enquirer.set method with untrusted input for the question.name parameter is at risk. This includes CLI tools, interactive scripts, and automation frameworks that leverage enquirer for user interaction. Indirect exposure occurs in projects that consume enquirer as a transitive dependency without version constraints.

Exploitability

Exploitation is straightforward: an attacker who has already authenticated to an application or service using enquirer can craft a malicious question.name value to pollute the Object.prototype. The attack is not complex and does not require user interaction. Public exploit code has been released, reducing the barrier to weaponization. However, the requirement for prior authentication significantly limits opportunistic attacks; this is not a wormable or pre-auth vulnerability.

Remediation

Upgrade enquirer to a version that patches this vulnerability—consult the enquirer GitHub repository or npm package advisories for the specific patched release. For applications where immediate patching is not feasible, implement input validation and sanitization on question.name parameters before passing them to Enquirer.set, and consider restricting usage of enquirer to trusted internal tools only. Review and audit any applications that use enquirer with user-supplied data.

Patch guidance

Check the enquirer npm package repository and official release notes for versions newer than 2.4.1 that address this prototype pollution issue. Apply the patched version across all dependencies—use npm audit to identify affected transitive dependencies and update package-lock.json accordingly. Test compatibility of the patched version with your application before deploying to production, as prototype pollution fixes sometimes require small API adjustments.

Detection guidance

Monitor for suspicious modifications to Object.prototype in runtime environments, particularly in Node.js applications using enquirer. Check application logs and process execution traces for calls to Enquirer.set with unusual or suspicious question.name values (e.g., containing proto, constructor, or prototype strings). npm audit and SBOM scanning tools will flag vulnerable versions of enquirer in your dependency tree. Consider adding lint rules to detect prototype pollution patterns in code review.

Why prioritize this

Although CVSS 4.3 is rated MEDIUM, this vulnerability merits priority for organizations heavily invested in Node.js tooling and CLI automation. The public availability of exploit code and the authenticated-but-common nature of the attack vector mean that insider threats and compromised service accounts could abuse this flaw. Prioritize teams building developer-facing tools and those managing shared internal CLI utilities.

Risk score, explained

The CVSS 3.1 score of 4.3 reflects a network-accessible vulnerability with low attack complexity, but mitigated by the requirement for prior authentication (PR:L) and limited scope (S:U). The integrity impact (I:L) is the primary concern—no confidentiality or availability compromise occurs. This places the risk in the MEDIUM band. The actual risk to your organization depends on how widely enquirer is used internally and whether user-facing authentication systems rely on it.

Frequently asked questions