CVE-2026-54312: n8n Prototype Pollution in Microsoft SQL Node (CVSS 8.5 HIGH)

Technical summary

This is a prototype pollution vulnerability (CWE-1321) in the Microsoft SQL node implementation prior to n8n 2.24.0. An authenticated user can inject a crafted payload via the table parameter that modifies Object.prototype, a shared object at the top of JavaScript's prototype chain. This pollution persists for the lifetime of the Node.js process and breaks downstream validation checks across the entire application by introducing unexpected properties into all object instances. The attack surface is bounded to users with workflow creation or modification privileges, but once triggered, the impact is process-wide and requires server restart to recover.

Business impact

A compromised n8n account or insider threat can disable the entire automation platform without causing data theft or confidentiality loss. This denial of service renders all workflows non-functional, halting business process automation until the server is restarted and the workflow is corrected or removed. For organizations heavily dependent on n8n for critical integrations, even brief outages disrupt downstream systems. The attack leaves no persistent damage to data or configuration—only service interruption—but the impact is severe for availability-dependent use cases.

Affected systems

n8n versions prior to 2.24.0 are affected. The vulnerability is specific to the Microsoft SQL node and requires the attacker to hold a valid n8n user account with permissions to create or edit workflows. Self-hosted and cloud-hosted deployments are both vulnerable if running unpatched versions. Organizations using n8n without Microsoft SQL node integration may have reduced attack surface if that node is not exposed to untrusted users.

Exploitability

Exploitability is moderate. The attack requires valid authentication and workflow modification permissions, so mass exploitation is unlikely unless accounts are compromised or overly permissive role assignments exist. No user interaction or social engineering is required once the attacker gains access. The attack is trivial to execute—a single crafted parameter value—making it attractive to insiders or account-compromise scenarios. Public exploit code is not required; the vulnerability is straightforward to weaponize from the description alone.

Remediation

Upgrade to n8n version 2.24.0 or later, which patches the prototype pollution in the Microsoft SQL node. If immediate upgrade is impossible, restrict workflow creation and modification permissions to trusted users only, and monitor for signs of account compromise. Consider temporarily disabling the Microsoft SQL node in affected environments if it is not actively used. No compensating controls fully mitigate the vulnerability without patching.

Patch guidance

Apply the n8n 2.24.0 release or later as soon as feasible. Verify the patch is deployed across all n8n instances in your environment, including self-hosted and containerized deployments. Test patched instances in a non-production environment first to confirm no workflow regressions. If you maintain custom patches or forks, backport the fix from the official 2.24.0 release to your version. Monitor release notes for any follow-up patches addressing related prototype pollution vectors.

Detection guidance

Monitor n8n server logs for failed validation errors or unexpected exceptions occurring shortly after workflow modifications, which may indicate prototype pollution. Watch for repeated server restarts or service disruptions among teams using n8n. Review workflow modification audit logs to identify who created or edited workflows containing suspicious Microsoft SQL node configurations with unusual table parameter values. Use static analysis on workflow JSON exports to detect parameter values that might include prototype-pollution payloads (e.g., __proto__, constructor, prototype). Monitor process behavior for unexpected property additions to global objects if running n8n in an instrumented environment.

Why prioritize this

This vulnerability merits rapid patching because it provides a complete denial of service to a critical workflow platform with minimal exploitation barriers for authenticated attackers. The HIGH CVSS score (8.5) reflects the combination of low attack complexity, scope change, and high availability impact. While it does not leak data or enable code execution, the process-wide nature of the pollution and the mandatory restart requirement make it operationally severe. Insider threats and account compromise are realistic attack vectors in multi-tenant or open n8n deployments, justifying swift remediation.

Risk score, explained

CVE-2026-54312 scores 8.5 (HIGH) under CVSS 3.1 due to network-accessible attack surface (AV:N), low attack complexity (AC:L), low privilege requirements (PR:L), lack of user interaction (UI:N), changed scope (S:C), no confidentiality impact (C:N), minor integrity impact (I:L), and high availability impact (A:H). The changed scope reflects that the vulnerability affects services and systems beyond the n8n process itself when workflow automation triggers are blocked. The high availability score dominates the risk rating because process-wide pollution renders the entire platform non-functional.

Frequently asked questions