A flaw in Node.js HMAC verification uses a non-constant-time comparison when validating user-provided signatures, potentially leaking timing… (CVE-2026-21713)
Node.js contains a vulnerability in its HMAC verification process where a non-constant-time comparison is used to validate user-provided signatures. This flaw can leak timing information proportional to the number of matching bytes, potentially allowing an attacker with high-resolution timing capabilities to infer HMAC values. The issue affects multiple Node.js versions across 20.x, 21.x, 22.x, 23.x, 24.x, and 25.x branches. A patch is available to address this vulnerability.
AI Analysis
Technical Summary
The vulnerability in Node.js (CVE-2026-21713) arises from the use of a non-constant-time comparison function during HMAC signature verification. This timing side-channel can leak information about the number of matching bytes in the signature, which under certain threat models could be exploited as a timing oracle to recover HMAC values. Node.js has timing-safe comparison primitives elsewhere, indicating this flaw is an oversight. The affected versions include <20.20.2, >=21.0.0 <22.22.2, >=23.0.0 <24.14.1, and >=25.0.0 <25.8.2. A patch is available to fix this issue.
Potential Impact
An attacker capable of making high-resolution timing measurements against the vulnerable HMAC verification function may be able to infer partial or full HMAC values by exploiting the timing leak. This could undermine the integrity guarantees provided by HMAC in affected Node.js versions. There are no known exploits in the wild at this time.
Mitigation Recommendations
A patch is available for this vulnerability. Users should upgrade to fixed versions at or beyond 20.20.2, 22.22.2, 24.14.1, and 25.8.2 to remediate the issue. Applying the official updates will ensure the use of timing-safe comparison functions during HMAC verification.
A flaw in Node.js HMAC verification uses a non-constant-time comparison when validating user-provided signatures, potentially leaking timing… (CVE-2026-21713)
Description
Node.js contains a vulnerability in its HMAC verification process where a non-constant-time comparison is used to validate user-provided signatures. This flaw can leak timing information proportional to the number of matching bytes, potentially allowing an attacker with high-resolution timing capabilities to infer HMAC values. The issue affects multiple Node.js versions across 20.x, 21.x, 22.x, 23.x, 24.x, and 25.x branches. A patch is available to address this vulnerability.
Affected software
pkg:bitnami/nodeRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in Node.js (CVE-2026-21713) arises from the use of a non-constant-time comparison function during HMAC signature verification. This timing side-channel can leak information about the number of matching bytes in the signature, which under certain threat models could be exploited as a timing oracle to recover HMAC values. Node.js has timing-safe comparison primitives elsewhere, indicating this flaw is an oversight. The affected versions include <20.20.2, >=21.0.0 <22.22.2, >=23.0.0 <24.14.1, and >=25.0.0 <25.8.2. A patch is available to fix this issue.
Potential Impact
An attacker capable of making high-resolution timing measurements against the vulnerable HMAC verification function may be able to infer partial or full HMAC values by exploiting the timing leak. This could undermine the integrity guarantees provided by HMAC in affected Node.js versions. There are no known exploits in the wild at this time.
Mitigation Recommendations
A patch is available for this vulnerability. Users should upgrade to fixed versions at or beyond 20.20.2, 22.22.2, 24.14.1, and 25.8.2 to remediate the issue. Applying the official updates will ensure the use of timing-safe comparison functions during HMAC verification.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- BIT-node-2026-21713
- Osv Schema Version
- 1.6.2
- Aliases
- ["CVE-2026-21713"]
- Ecosystems
- ["Bitnami"]
- Database Specific Severity
- Medium
Threat ID: 6aa005faacd9273b49ab6885
Added to database: 09/08/2026, 12:56:26 UTC
Last enriched: 09/08/2026, 13:36:11 UTC
Last updated: 09/10/2026, 19:36:52 UTC
Views: 36
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