What’s Vulnerable › Vulnerabilities

CVE-2021-41167: Unlimited requests in modern-async

• Severity: medium (CVSS 5.0 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-10-20 · updated 2026-06-17
• Weakness: CWE-400

Description

modern-async is an open source JavaScript tooling library for asynchronous operations using async/await and promises. In affected versions 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. The problem has been patched in 1.0.4. There is no workaround.

Affected products

• nicolas-van modern-async: before 1.0.4 — fixed in 1.0.4

How to fix

Upgrade to a fixed version: nicolas-van modern-async 1.0.4. Check the vendor advisory for mitigations.

References

• https://github.com/nicolas-van/modern-async/commit/0010d28de1b15d51db3976080e26357fa7144436
• https://github.com/nicolas-van/modern-async/issues/5
• https://github.com/nicolas-van/modern-async/security/advisories/GHSA-3pcq-34w5-p4g2
• https://github.com/nicolas-van/modern-async/commit/0010d28de1b15d51db3976080e26357fa7144436
• https://github.com/nicolas-van/modern-async/issues/5
• https://github.com/nicolas-van/modern-async/security/advisories/GHSA-3pcq-34w5-p4g2

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