CVE-2026-21713

Published Mar 30, 2026

Last updated 18 days ago

Overview

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**.
Source
support@hackerone.com
NVD status
Analyzed
Products
node.js

Risk scores

CVSS 3.0

Type
Secondary
Base score
5.9
Impact score
3.6
Exploitability score
2.2
Vector string
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Severity
MEDIUM

Weaknesses

134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-208

Social media

Hype score
Not currently trending

Configurations

References

Sources include official advisories and independent security research.