Vulnerabilities in pkg:npm/sse-channel

PACKAGE
Advisory Identifier: GHSA-84hm-wfh8-c5pg
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Advisory Summary

CVE-2026-44217 is a MODERATE sse injection vulnerability (CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')) affecting sse-channel libraries in the npm ecosystem. The issue involves sse injection via unsanitized event fields. Remediation is available by upgrading affected packages to version 4.0.1.

1 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/sse-channel

1 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:npm/sse-channel. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-84hm-wfh8-c5pg CVE-2026-44217 MODERATE sse-channel: SSE Injection via unsanitized event fields

CVE-2026-44217 at a Glance

CVE Identifier CVE-2026-44217
GHSA Identifier GHSA-84hm-wfh8-c5pg
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')
Affected Product sse-channel
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-44217

To remediate this vulnerability, upgrade all affected sse-channel dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

sse-channel fixed: 4.0.1 
npm install sse-channel@4.0.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls sse-channel

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-44217, inspect your project dependencies using npm:

npm ls sse-channel

Analyze the terminal output to locate any version of sse-channel in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.0.1), your application is affected.

Note: The npm ls sse-channel command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection'), where the product uses crlf (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes crlf sequences from inputs. In sse-channel, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Implementations that allows user-provided values to be passed to `event`, `retry` or `id` fields would be susceptible to event spoofing, where an attacker could inject arbitrary messages into the stream. - **Event Spoofing:** Attacker can inject arbitrary SSE events into the stream - **Client-side Manipulation:** Injected events can trigger unintended behavior in frontend JavaScript EventSource listeners - **Data Integrity:** Consumers of the SSE stream cannot distinguish injected events from legitimate ones ### Patches Patch available in v4.0.1. ### Workarounds Do not allow user data to control `event`, `retry` or `id` fields, and if you must - sanitize the input before passing it to `sse-channel`, stripping any newlines. ### Resources https://github.com/rexxars/sse-channel/issues/42

CVE-2026-44217 Affected sse-channel Versions

1 component(s)
Fixed Versions:
4.0.1
Product / Package Ecosystem Affected Versions Fixed Version
sse-channel
npm/sse-channel
npm
< 4.0.1
4.0.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/rexxars/sse-channel/security/advisories/GHSA-84hm-wfh8-c5pg
NVD — CVE-2026-44217 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-44217
sse-channel Source Repository REPOSITORY
https://github.com/rexxars/sse-channel/issues/42
sse-channel Source Repository REPOSITORY
https://github.com/rexxars/sse-channel

Frequently Asked Questions

What is CVE-2026-44217?
CVE-2026-44217 is a security vulnerability in sse-channel involving SSE Injection via unsanitized event fields under CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection').
Which sse-channel versions are affected?
Affected versions include releases prior to 4.0.1 across affected packages: sse-channel.
What version fixes CVE-2026-44217?
Upgrading to 4.0.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is sse-channel affected?
Yes, sse-channel is affected in releases prior to 4.0.1. Upgrade your dependency to 4.0.1 or later.
What CWE is associated with CVE-2026-44217?
CVE-2026-44217 is classified under CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection') (The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.).
How can I check npm dependencies for CVE-2026-44217?
Run the dependency tree command: 'npm ls sse-channel'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-84hm-wfh8-c5pg",
  "modified" : "2026-05-13T16:27:28Z",
  "published" : "2026-05-05T22:17:02Z",
  "aliases" : [ "CVE-2026-44217" ],
  "summary" : "sse-channel: SSE Injection via unsanitized event fields",
  "details" : "### Impact\n\nImplementations that allows user-provided values to be passed to `event`, `retry` or `id` fields would be susceptible to event spoofing, where an attacker could inject arbitrary messages into the stream.\n\n- **Event Spoofing:** Attacker can inject arbitrary SSE events into the stream\n- **Client-side Manipulation:** Injected events can trigger unintended behavior in frontend JavaScript EventSource listeners\n- **Data Integrity:** Consumers of the SSE stream cannot distinguish injected events from legitimate ones\n\n### Patches\nPatch available in v4.0.1.\n\n### Workarounds\nDo not allow user data to control `event`, `retry` or `id` fields, and if you must - sanitize the input before passing it to `sse-channel`, stripping any newlines. \n\n### Resources\n\nhttps://github.com/rexxars/sse-channel/issues/42",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "sse-channel"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.0.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.0.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/rexxars/sse-channel/security/advisories/GHSA-84hm-wfh8-c5pg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44217"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rexxars/sse-channel/issues/42"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/rexxars/sse-channel"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-93" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-05T22:17:02Z",
    "nvd_published_at" : "2026-05-12T20:16:42Z"
  }
}