medium5.9
CVE-2026-21713
A flaw in Node.js HMAC verification uses a non-constant-time comparison when validating user-provided signatures, potentially leaking timing information propor…
Impact
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
| Vendor | Product | Affected versions |
|---|---|---|
| Nodejs | 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 |