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nodejs node: A flaw in Node.js HMAC verification uses a non-constant-time comparison when validating user-provided signatures, potent

Node.js · CVE-2026-21713
0 news outlets0 CERTs and agencies0 researchers

What is it?

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**.

Evidence

No coverage recorded yet.

Exploitation

  • Public proof of concept
  • Exploited in the wild
  • Listed as known exploited
CVSS
5.9
EPSS
0.4%
First seen
10 h ago
Status
corroborated

All Node.js vulnerabilities