Improper Input Validation in Nest Framework for Node.js Applications
CVE-2026-35515

6.3MEDIUM

Key Information:

Vendor

Nestjs

Status
Nest
Vendor
CVE Published:
7 April 2026

What is CVE-2026-35515?

The Nest Framework, a popular platform for creating scalable server-side applications in Node.js, contains a vulnerability in its version prior to 11.1.18. The issue lies in the SseStream._transform() method, which improperly handles newline characters in the Server-Sent Events (SSE) protocol. Due to a lack of input sanitization, an attacker can manipulate message.type and message.id fields to inject arbitrary SSE events. This can lead to spoofing event types and potentially corrupting the application's reconnection state. Developers are encouraged to upgrade to version 11.1.18 or later to mitigate this risk.

Affected Version(s)

nest < 11.1.18

References

https://github.com/nestjs/nest/security/advisories/GHSA-3...
x_refsource_CONFIRM

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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