What is GHSA-MH6F-8J2X-4483?

GHSA-MH6F-8J2X-4483 is a critical-severity security vulnerability in event-stream (npm), affecting versions = 3.3.6. It is fixed in 4.0.0.

How severe is GHSA-MH6F-8J2X-4483?

GHSA-MH6F-8J2X-4483 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which packages are affected by GHSA-MH6F-8J2X-4483?

event-stream (npm) versions = 3.3.6; flatmap-stream (npm) versions >= 0.

Is there a fix for GHSA-MH6F-8J2X-4483?

Yes. GHSA-MH6F-8J2X-4483 is fixed in 4.0.0. Upgrade to this version or later.

Is GHSA-MH6F-8J2X-4483 exploitable, and should I be worried?

Whether GHSA-MH6F-8J2X-4483 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether GHSA-MH6F-8J2X-4483 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

GHSA-MH6F-8J2X-4483 in event-stream

Q: How do I fix GHSA-MH6F-8J2X-4483?

Upgrade event-stream to 4.0.0 or later.

Summary

Critical severity vulnerability that affects event-stream and flatmap-stream

The NPM package flatmap-stream is considered malicious. A malicious actor added this package as a dependency to the NPM event-stream package in version 3.3.6. Users of event-stream are encouraged to downgrade to the last non-malicious version, 3.3.4, or upgrade to the latest 4.x version.

Users of flatmap-stream are encouraged to remove the dependency entirely.

Impact

GHSA-MH6F-8J2X-4483 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.0.0); upgrading removes the vulnerable code path.

Affected versions

event-stream (= 3.3.6) flatmap-stream (>= 0)

Security releases

event-stream → 4.0.0 (npm)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade event-stream to 4.0.0 or later to resolve this vulnerability.

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is GHSA-MH6F-8J2X-4483? GHSA-MH6F-8J2X-4483 is a critical-severity security vulnerability in event-stream (npm), affecting versions = 3.3.6. It is fixed in 4.0.0.
How severe is GHSA-MH6F-8J2X-4483? GHSA-MH6F-8J2X-4483 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which packages are affected by GHSA-MH6F-8J2X-4483?
- event-stream (npm) (versions = 3.3.6)
- flatmap-stream (npm) (versions >= 0)
Is there a fix for GHSA-MH6F-8J2X-4483? Yes. GHSA-MH6F-8J2X-4483 is fixed in 4.0.0. Upgrade to this version or later.
Is GHSA-MH6F-8J2X-4483 exploitable, and should I be worried? Whether GHSA-MH6F-8J2X-4483 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether GHSA-MH6F-8J2X-4483 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix GHSA-MH6F-8J2X-4483? Upgrade event-stream to 4.0.0 or later.