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Vulnerability record · CVE-2026-21713 · published 30 March 2026

CVE-2026-21713: Nodejs node.js vulnerability

Nodejs · Node.Js

A flaw in Node.js HMAC verification uses a non-constant-time comparison when validating user-provided signatures, potentially leaking timing information proportional to the number of matching bytes. Under certain threat models where high-resolution timing measurements are possible, this behavior could be exploited as a timing oracle to infer HMAC values. Node.js already provides timing-safe comparison primitives used elsewhere in the codebase, indicating this is an oversight rather than an intentional design decision. This vulnerability affects **20.x, 22.x, 24.x, and 25.x**.

5.9 CVSS 3.0 Medium EPSS 0.39% · top 70.0% CWE-208 · CWE-208
5.9CVSS 3.0 base score
0.39%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
1References
19 Aug 2026Last modified by NVD

Description

A flaw in Node.js HMAC verification uses a non-constant-time comparison when validating user-provided signatures, potentially leaking timing information proportional to the number of matching bytes. Under certain threat models where high-resolution timing measurements are possible, this behavior could be exploited as a timing oracle to infer HMAC values. Node.js already provides timing-safe comparison primitives used elsewhere in the codebase, indicating this is an oversight rather than an intentional design decision. This vulnerability affects **20.x, 22.x, 24.x, and 25.x**.

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://nodejs.org/en/blog/vulnerability/march-2026-security-releases Vendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2026-21713), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.