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...
- Published
- Mar 30, 2026
- Updated
- May 10, 2026
- Assigning CNA
- hackerone
- Evidence observed
- Aug 25, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HLow · next 30 days
- Percentile
- 19.2%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
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**.
Sources
1Proof-of-concept for CVE-2026-21717, a Node.js V8 string hashing collision vulnerability causing denial of service via crafted JSON payloads.
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