What’s Vulnerable › Vulnerabilities
CVE-2026-21713
- Severity: medium (CVSS 5.9 v3.0)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.4% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-03-30 · updated 2026-08-19
- Weakness: CWE-208
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**.
Affected products
- Node.js: through 20.20.1; from 22.0.0 through 22.22.1; from 24.0.0 through 24.14.0; from 25.0.0 through 25.8.1
References
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