CVE-2026-77075

CVE-2026-77075 is a cross-user expression injection vulnerability in n8n's link preview rendering path. When a user opens a workflow containing malicious expressions in resource-locator field values, the preview renderer evaluates those expressions server-side using n8n's JavaScript expression engine—executing arbitrary code in the victim's authenticated session. The attacker need only embed a crafted expression; victim interaction (opening the workflow editor) triggers execution. This is not a missing sanitization check—it is a trust model failure where n8n's architecture treats shared workflow state as implicitly trusted, contradicting the expression engine's ability to execute arbitrary JavaScript. The severity is amplified by what n8n workflows contain: OAuth tokens, API keys, database credentials, and integration permissions to external SaaS platforms. An expression executing in a victim's session can access these stored credentials directly, pivoting from session compromise into the victim's entire connected infrastructure—Salesforce, Stripe, GitHub, or any system the workflow touches. The CVSS score of 8.4 materially understates this blast radius because it cannot capture the credential density of a workflow-centric attack. The patch addresses the link preview path specifically. However, the underlying architectural issue is systemic: n8n's expression engine has no concept of execution context—it evaluates expressions identically whether in workflow execution or UI rendering. Every feature that touches stored workflow state is a potential vector until the trust model changes. Specifically, audit for expression evaluation in deprecated features, admin interfaces, error rendering paths, and logging—places where the same implicit trust in stored workflow data likely persists but receives less scrutiny. Immediate actions: apply the patch, then audit shared workflows in your instance for suspicious expression syntax in field values. Consider rotating OAuth tokens and API keys in workflows that were shared before the patch, as malicious payloads may have been embedded and remain dormant until opened. The longer-term question is whether n8n's expression system should decouple preview rendering from expression evaluation entirely—serving static previews to editors while reserving full evaluation for explicit workflow execution.

Reviewed through automated stages and approved by a human before publication.