CVE-2026-25224

Fastify Vulnerable to DoS via Unbounded Memory Allocation in sendWebStream

LOW
3.7
CVSS Score
Published: February 3, 2026 at 09:21 PM UTC
Updated: June 17, 2026 at 10:24 AM UTC
1 product affected across 1 vendorFastify

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Severity
LOW3.7
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 5.7.3
Affected range stops below 5.7.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

x_refsource_CONFIRMVendor Advisory
Source: cverecord
https://github.com/fastify/fastify/security/advisories/GHSA-mrq3-vjjr-p77c
x_refsource_MISCPermissions Required
Source: cverecord
https://hackerone.com/reports/3524779

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

3.7LOWGitHub_M
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusANALYZED
CWE
CWE-770

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