CVE-2026-21713

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**.

How to fix CVE-2026-21713

To remediate CVE-2026-21713, upgrade the affected package to a fixed version below.

• —upgrade to 22.22.2-r0 or later
• —upgrade to 20.20.2 or later
• —upgrade to 20.20.2 or later
• —upgrade to 18.20.4+dfsg-1~deb12u2 or later

Is CVE-2026-21713 being exploited?

Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.

Affected packages (4)

• from 0, < 22.22.2-r0
• from 0, < 20.20.2, >= 21.0.0, < 22.22.2, >= 23.0.0, < 24.14.1, >= 25.0.0, < 25.8.2
• from 0, < 20.20.2, >= 21.0.0, < 22.22.2, >= 23.0.0, < 24.14.1, >= 25.0.0, < 25.8.2
• from 0, < 18.20.4+dfsg-1~deb12u2

CVSS scores

References (4)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2026-21713
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-21713
• WEBnodejs.org/en/blog/vulnerability/march-2026-security-releases
• WEBnvd.nist.gov/vuln/detail/CVE-2026-21713