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CVE-2026-21717

MEDIUMCVSS 5.9/10EPSS 0.28%

Last modified

CVE-2026-21717 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. 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**.. EPSS estimates a 0.28% chance of exploitation in the next 30 days.

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**.

Metrics

CVSS 3.0
5.9/10

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
0.28%

20.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
nodejsnode>= 20.20.1, <= 20.20.1; >= 22.22.1, <= 22.22.1; >= 24.14.0, <= 24.14.0; >= 25.8.1, <= 25.8.1; >= 4.0, < 4.*; >= 5.0, < 5.*; >= 6.0, < 6.*; >= 7.0, < 7.*; >= 8.0, < 8.*; >= 9.0, < 9.*; >= 10.0, < 10.*; >= 11.0, < 11.*; >= 12.0, < 12.*; >= 13.0, < 13.*; >= 14.0, < 14.*; >= 15.0, < 15.*; >= 16.0, < 16.*; >= 17.0, < 17.*; >= 18.0, < 18.*; >= 19.0, < 19.*

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is 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**.
How severe is CVE-2026-21717?
CVE-2026-21717 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 0.28% probability of exploitation in the next 30 days.
How do I fix CVE-2026-21717?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST