CVE-2026-110854 in parse-server
Summary
by MITRE • 10/15/2026
Parse Server before 8.6.97 and 9.0.0 before 9.10.2-alpha.6 does not handle errors raised while sending verification or password reset emails, causing the server process to exit. A client holding only the public application keys can sign up, request a verification email, or request a password reset while the mail provider rejects, rate limits, or is unavailable, crashing the server.
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Analysis
by VulDB Data Team • 10/15/2026
Parse Server versions prior to 8.6.97 and 9.0.0 before 9.10.2-alpha.6 contain a critical reliability flaw in their email notification subsystem that results in an unhandled exception leading to process termination. This vulnerability specifically affects the mechanisms responsible for sending verification emails during user registration and password reset tokens upon request. The root cause lies in insufficient error handling within the asynchronous operations that interface with external mail transport agents or SMTP services. When these external services respond with rejection codes, enforce rate limiting policies, or become entirely unavailable due to network issues or service outages, the Parse Server instance fails to catch the resulting exception properly. Instead of gracefully degrading or returning a standard error response to the client, the unhandled promise rejection propagates up the call stack and terminates the Node.js event loop, causing the entire server process to crash immediately.
The operational impact of this vulnerability is severe for any production environment relying on Parse Server as its backend infrastructure. Because the flaw allows an attacker with only public application keys—which are inherently exposed in client-side applications—to trigger a denial-of-service condition, it represents a significant availability risk. An adversary can systematically send requests to sign up new users or request password resets while ensuring that the mail provider rejects these messages or is unreachable. By repeatedly triggering this state, the attacker can induce repeated crashes of the server process, effectively rendering the application unavailable to legitimate users. This constitutes a classic denial-of-service scenario where low-privilege actors can disrupt service continuity without requiring authentication or elevated permissions, exploiting the lack of robust fault tolerance in critical user-facing workflows.
From a vulnerability classification perspective, this issue aligns with CWE-754: Improper Check for Unusual or Exceptional Conditions and CWE-248: Unhandled Error. The failure to handle exceptions arising from external service interactions violates fundamental principles of defensive programming where all I/O operations must be wrapped in appropriate try-catch blocks or promise rejection handlers. In the context of the MITRE ATT&CK framework, this vulnerability facilitates Denial of Service via Impactful Actions, specifically targeting Availability through resource exhaustion caused by process crashes rather than traditional CPU or memory saturation techniques. The attack vector is remote and requires no authentication beyond public keys, making it easily exploitable in most web-based deployments where client-side code exposes these identifiers.
Mitigation strategies must focus on immediate patching as well as architectural resilience improvements. Organizations running affected versions of Parse Server should upgrade to version 8.6.97 or later for the 8.x branch, or version 9.10.2-alpha.6 and later for the 9.x branch, where these error handling mechanisms have been corrected to prevent process termination upon mail delivery failures. In addition to patching, administrators should implement external monitoring solutions that detect service unavailability quickly and attempt automatic restarts if crashes occur during the transition period. Furthermore, integrating a retry mechanism with exponential backoff for email sending operations can help mitigate transient network issues or temporary rate limiting by providers without triggering fatal errors. Ensuring that all asynchronous database and network calls are properly awaited and wrapped in error-handling logic is essential to maintaining high availability standards across distributed systems relying on Parse Server infrastructure.