Information Exposure Through Timing Discrepancy in Node.js - CVE-2026-21713
Published: March 25, 2026
Vulnerability identifier: #VU124545
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-21713
CWE-ID: CWE-208
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Node.js Foundation
Affected software:
Node.js
Node.js
Detailed vulnerability description
The vulnerability allows a remote attacker to potentially forge message authentication codes.
The vulnerability exists due to use of non-constant-time comparison in HMAC verification in crypto_hmac.cc when validating user-provided signatures. A remote attacker can measure timing differences during signature comparison to infer valid HMAC values, acting as a timing oracle.
Exploitation requires high-resolution timing measurements and repeated queries under a favorable threat model.
How to mitigate CVE-2026-21713
Install security update from vendor's website.