Vulnerability in Node.js Node
CVE-2026-21717
A flaw in V8's string hashing mechanism causes integer-like strings to be hashed to their numeric value, making hash collisions trivially predictable. By crafting a request that causes many such collisions in V8's internal string table, an attacker can significantly degrade performance of the Node.js process. The most common trigger is any endpoint that calls `JSON.parse()` on attacker-controlled input, as JSON parsing automatically internalizes short strings into the affected hash table. This vulnerability affects **20.x, 22.x, 24.x, and 25.x**.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.003 (17.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 17th percentile — 17.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Node.js Node — versions 20.20.1, 22.22.1, 24.14.0
- Node.js
Weakness classification (CWE)
Public proof-of-concept exploits
References
- nodejs.org/en/blog/vulnerability/march-2026-security-releases (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-21717?
- CVE-2026-21717 is a medium-severity vulnerability in Node.js Node, classified under Use of Weak Hash. CVSS score: 5.9/10. Published 2026-03-30.
- How severe is CVE-2026-21717?
- Medium severity. CVSS v3 base score is 5.9 out of 10.
- Is CVE-2026-21717 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.