Resource exhaustion in Fastify
CVE-2026-25224
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.005 (41.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 42nd percentile — 41.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: +0.000
Affected products
- Fastify — versions < 5.7.3
Weakness classification (CWE)
References
- github.com/fastify/fastify/security/advisories/GHSA-mrq3-vjjr-p77c (Vendor Advisory)
- github.com/fastify/fastify/commit/eb11156396f6a5fedaceed0140aed2b7f026be37 (Patch)
- hackerone.com/reports/3524779 (Permissions Required)
Frequently asked questions
- What is CVE-2026-25224?
- CVE-2026-25224 is a low-severity vulnerability in Fastify, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 3.7/10. Published 2026-02-03.
- How severe is CVE-2026-25224?
- Low severity. CVSS v3 base score is 3.7 out of 10.