CVE-2026-35515

@nestjs/core Improperly Neutralizes Special Elements in Output Used by a Downstream Component ('Injection')

MEDIUM
6.1
CVSS Score
Published: April 7, 2026 at 03:06 PM UTC
Updated: October 26, 2026 at 09:10 PM UTC
1 product affected across 1 vendorNest

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Severity
MEDIUM6.1
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 11.1.18
Affected range stops below 11.1.18, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

x_refsource_CONFIRMVendor Advisory
Source: cverecord
https://github.com/nestjs/nest/security/advisories/GHSA-36xv-jgw5-4q75

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusANALYZED
CWE
CWE-74

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