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Servers and applications

CVE-2026-21713

Timing side-channel in HMAC verification via `memcmp()` in `crypto_hmac.cc` leads to potential MAC forgery

Severity
Medium 5.9
Published
24 Mar 2026
Last changed
19 Aug 2026
Added to UpHeron
21 Oct 2026
Fixed in
20.20.2, 22.22.2, 24.14.1, 25.8.2
Sources
NVD, nodejs

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…

Affected software

SoftwareAffected versions
Node.jsServers and applications · cpe:a:nodejs:node.js
  • From 25.0.0 up to 25.8.1
  • From 25.0.0 before 25.8.2
  • From 24.0.0 up to 24.14.0
  • From 24.0.0 before 24.14.1
All 8 release lines
  • Every version up to 20.20.1
  • From 20.0.0 before 20.20.2
  • From 22.0.0 before 22.22.2
  • From 22.0.0 up to 22.22.1
  • From 24.0.0 before 24.14.1
  • From 24.0.0 up to 24.14.0
  • From 25.0.0 before 25.8.2
  • From 25.0.0 up to 25.8.1

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2026-21713
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2026-21713
  • Node.js security release https://nodejs.org/en/blog/vulnerability/march-2026-security-releases