CVE Catalog

CVE-2026-35515

MediumCVSS 6.1
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.23%

14th percentile - higher than 14% of all known CVEs

Summary

Nest, a framework for building scalable Node.js server-side applications, prior to 11.1.18 interpolates message.type and message.id directly into Server-Sent Events text protocol output in SseStream._transform() without sanitizing newline characters (\r, \n). Since the SSE protocol treats these as field delimiters, an attacker able to influence these fields can inject arbitrary SSE events, spoof event types, and corrupt reconnection state.

Risk Assessment

Possible injection of forged SSE events to clients, event type spoofing, and disruption of reconnection logic, potentially causing application malfunction or attacks on clients.

Recommendation

Update Nest to version 11.1.18 or later.

Related vulnerabilities

Original NVD description (English source)

Nest is a framework for building scalable Node.js server-side applications. Prior to 11.1.18, SseStream._transform() interpolates message.type and message.id directly into Server-Sent Events text protocol output without sanitizing newline characters (\r, \n). Since the SSE protocol treats both \r and \n as field delimiters and \n\n as event boundaries, an attacker who can influence these fields through upstream data sources can inject arbitrary SSE events, spoof event types, and corrupt reconnection state. This vulnerability is fixed in 11.1.18.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS