CVE-2026-21717

State: Published
Severity: 5.9 Medium
Published: Mar 30, 2026
Updated: May 10, 2026
Reserved: Jan 4, 2026

Description

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**.

Scores

CVSS	Score	Vector	Source
3.0	5.9 Medium	CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H	hackerone

Weaknesses

CWE-328 Use of Weak Hash

Affected Products

Product	Versions
nodenodejs	20.20.1 through 20.20.1Affected 22.22.1 through 22.22.1Affected 24.14.0 through 24.14.0Affected 25.8.1 through 25.8.1Affected 4.0 to before 4.Affected 5.0 to before 5.Affected 6.0 to before 6.Affected 7.0 to before 7.Affected 8.0 to before 8.Affected 9.0 to before 9.Affected 10.0 to before 10.Affected 11.0 to before 11.Affected 12.0 to before 12.Affected 13.0 to before 13.Affected 14.0 to before 14.Affected 15.0 to before 15.Affected 16.0 to before 16.Affected 17.0 to before 17.Affected 18.0 to before 18.Affected 19.0 to before 19.Affected

Product

Versions

nodenodejs

20.20.1 through 20.20.1Affected
22.22.1 through 22.22.1Affected
24.14.0 through 24.14.0Affected
25.8.1 through 25.8.1Affected
4.0 to before 4.*Affected
5.0 to before 5.*Affected
6.0 to before 6.*Affected
7.0 to before 7.*Affected
8.0 to before 8.*Affected
9.0 to before 9.*Affected
10.0 to before 10.*Affected
11.0 to before 11.*Affected
12.0 to before 12.*Affected
13.0 to before 13.*Affected
14.0 to before 14.*Affected
15.0 to before 15.*Affected
16.0 to before 16.*Affected
17.0 to before 17.*Affected
18.0 to before 18.*Affected
19.0 to before 19.*Affected

References

https://nodejs.org/en/blog/vulnerability/march-2026-security-releases

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