How severe is CVE-2026-21717?

CVE-2026-21717 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-21717 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21717?

CVE-2026-21717 affects Nodejs Node.js. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21717?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-21717 have an EU (EUVD) identifier?

Yes. CVE-2026-21717 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17182.

When was CVE-2026-21717 published?

CVE-2026-21717 was published on 2026-03-30 and last updated on 2026-08-19.

CVE-2026-21717

CVE-2026-21717 is a medium-severity vulnerability in Nodejs Node.js with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-328.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-17182
Weakness: CWE-328
Affected product: Nodejs Node.js
Published: 2026-03-30
Last modified: 2026-08-19

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**.

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 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-21717 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21717?: CVE-2026-21717 affects Nodejs Node.js. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21717?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21717 have an EU (EUVD) identifier?: Yes. CVE-2026-21717 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17182.
When was CVE-2026-21717 published?: CVE-2026-21717 was published on 2026-03-30 and last updated on 2026-08-19.

References

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

Affected products (1)

cpe:2.3:a:nodejs:node.js:*:*:*:*:-:*:*:*

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