CVE-2026-21713
A flaw in Node.js HMAC verification uses a non-constant-time comparison when validating user-provided signatures, potentially leaking…
- Published
- Updated
- Reserved
- Assigned by
- hackerone
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**.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| hackeroneCNA (assigner) | 3.0 | Medium5.9 | CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
| NVDNVD · Analyzed | 3.0 | Medium5.9 | CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
- EPSS (exploitation in 30 days)
- 0.37% · top 69% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.9.
Weakness
Affected products
- affected 20.20.1 – ≤ 20.20.1
- affected 22.22.1 – ≤ 22.22.1
- affected 24.14.0 – ≤ 24.14.0
- affected 25.8.1 – ≤ 25.8.1
- affected 4.0 – < 4.*
- affected 5.0 – < 5.*
- affected 6.0 – < 6.*
- affected 7.0 – < 7.*
- affected 8.0 – < 8.*
- affected 9.0 – < 9.*
- affected 10.0 – < 10.*
- affected 11.0 – < 11.*
- affected 12.0 – < 12.*
- affected 13.0 – < 13.*
- affected 14.0 – < 14.*
- affected 15.0 – < 15.*
- affected 16.0 – < 16.*
- affected 17.0 – < 17.*
- affected 18.0 – < 18.*
- affected 19.0 – < 19.*
References (1)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-21713)Record last updated .