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Vulnerability record · CVE-2026-25224 · published 3 February 2026

CVE-2026-25224: Fastify allocation without limits vulnerability

Fastify · Fastify

Fastify is a fast and low overhead web framework, for Node.js. Prior to version 5.7.3, a denial-of-service vulnerability in Fastify’s Web Streams response handling can allow a remote client to exhaust server memory. Applications that return a ReadableStream (or Response with a Web Stream body) via reply.send() are impacted. A slow or non-reading client can trigger unbounded buffering when backpressure is ignored, leading to process crashes or severe degradation. This issue has been patched in version 5.7.3.

3.7 CVSS 3.1 Low EPSS 0.52% · top 58.3% CWE-770 · Allocation without limits
3.7CVSS 3.1 base score
0.52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
17 Jun 2026Last modified by NVD

Description

Fastify is a fast and low overhead web framework, for Node.js. Prior to version 5.7.3, a denial-of-service vulnerability in Fastify’s Web Streams response handling can allow a remote client to exhaust server memory. Applications that return a ReadableStream (or Response with a Web Stream body) via reply.send() are impacted. A slow or non-reading client can trigger unbounded buffering when backpressure is ignored, leading to process crashes or severe degradation. This issue has been patched in version 5.7.3.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/fastify/fastify/commit/eb11156396f6a5fedaceed0140aed2b7f026be37 Patch
https://github.com/fastify/fastify/security/advisories/GHSA-mrq3-vjjr-p77c Vendor Advisory
https://hackerone.com/reports/3524779 Permissions Required

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-25224), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.