What is CVE-2021-41167?

CVE-2021-41167 is a high-severity uncontrolled resource consumption vulnerability in modern-async (npm), affecting versions < 1.0.4. It is fixed in 1.0.4. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.

How severe is CVE-2021-41167?

CVE-2021-41167 has a CVSS score of 7.5 (High). 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 versions of modern-async are affected by CVE-2021-41167?

modern-async (npm) versions < 1.0.4 is affected.

Is there a fix for CVE-2021-41167?

Yes. CVE-2021-41167 is fixed in 1.0.4. Upgrade to this version or later.

Is CVE-2021-41167 exploitable, and should I be worried?

Whether CVE-2021-41167 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 CVE-2021-41167 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 CVE-2021-41167?

Upgrade modern-async to 1.0.4 or later.

CVE-2021-41167 in modern-async

Q: How severe is CVE-2021-41167?

CVE-2021-41167 has a CVSS score of 7.5 (High). 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.

Q: Which versions of modern-async are affected by CVE-2021-41167?

modern-async (npm) versions < 1.0.4 is affected.

Q: Is there a fix for CVE-2021-41167?

Yes. CVE-2021-41167 is fixed in 1.0.4. Upgrade to this version or later.

Q: Is CVE-2021-41167 exploitable, and should I be worried?

Whether CVE-2021-41167 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.

Q: What actually determines whether CVE-2021-41167 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.

Q: How do I fix CVE-2021-41167?

Upgrade modern-async to 1.0.4 or later.

Summary

modern-async's forEachSeries and forEachLimit functions do not limit the number of requests

Workarounds

There is no workaround aside from upgrading to 1.0.4.

Impact

This is a bug affecting two of the functions in this library: forEachSeries and forEachLimit. They should limit the concurrency of some actions but, in practice, they don't. Any code calling these functions will be written thinking they would limit the concurrency but they won't. This could lead to potential security issues in other projects.

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

CVE-2021-41167 has a CVSS score of 7.5 (High). 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 (1.0.4); upgrading removes the vulnerable code path.

Affected versions

modern-async (< 1.0.4)

Security releases

modern-async → 1.0.4 (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

The problem has been patched in 1.0.4.

Frequently Asked Questions

What is CVE-2021-41167? CVE-2021-41167 is a high-severity uncontrolled resource consumption vulnerability in modern-async (npm), affecting versions < 1.0.4. It is fixed in 1.0.4. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
How severe is CVE-2021-41167? CVE-2021-41167 has a CVSS score of 7.5 (High). 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 versions of modern-async are affected by CVE-2021-41167? modern-async (npm) versions < 1.0.4 is affected.
Is there a fix for CVE-2021-41167? Yes. CVE-2021-41167 is fixed in 1.0.4. Upgrade to this version or later.
Is CVE-2021-41167 exploitable, and should I be worried? Whether CVE-2021-41167 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 CVE-2021-41167 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 CVE-2021-41167? Upgrade modern-async to 1.0.4 or later.