CVE-2026-21713

Node.js: Node.js: Information disclosure via timing oracle in HMAC verification

Published Mar 30, 2026 CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed
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**.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DSA Debian DSA DSA-6183-1 nodejs security update
Debian DSA Debian DSA DSA-6272-1 nodejs security update
History
Type Values Removed Values Added
First Time appeared Nodejs node.js
CPEs cpe:2.3:a:nodejs:node.js:*:*:*:*:-:*:*:*
Vendors & Products Nodejs node.js
Type Values Removed Values Added
Weaknesses CWE-203
Type Values Removed Values Added
Title Timing Side‑Channel in Node.js HMAC Verification Node.js: Node.js: Information disclosure via timing oracle in HMAC verification
First Time appeared Nodejs
Nodejs nodejs
Weaknesses CWE-208
Vendors & Products Nodejs
Nodejs nodejs
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'}

threat_severity

Moderate

Type Values Removed Values Added
Title Timing Side‑Channel in Node.js HMAC Verification
Weaknesses CWE-203
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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**.
References
Metrics cvssV3_0

{'score': 5.9, 'vector': 'CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
hackerone
Published
Updated
May 10, 2026, 1:17 PM
Reserved
Jan 4, 2026, 3:00 PM
Status
Analyzed
Published
Mar 30, 2026, 8:16 PM
Modified
Aug 19, 2026, 1:36 PM
Severity
Moderate
Public date
Mar 30, 2026, 7:07 PM