Vulnerability in Node.js Node
CVE-2026-21713
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**.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.004 (30.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 30.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Node.js Node — versions 20.20.1, 22.22.1, 24.14.0
- Node.js
Weakness classification (CWE)
References
- nodejs.org/en/blog/vulnerability/march-2026-security-releases (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-21713?
- CVE-2026-21713 is a medium-severity vulnerability in Node.js Node, classified under CWE-208. CVSS score: 5.9/10. Published 2026-03-30.
- How severe is CVE-2026-21713?
- Medium severity. CVSS v3 base score is 5.9 out of 10.