TI-2026-20374 Aliases CVE-2026-25224 GHSA-mrq3-vjjr-p77c

Fastify Vulnerable to DoS via Unbounded Memory Allocation in sendWebStream

LOW 18CWE-770Published 2026-02-03 · Updated 2026-02-04

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · Low
Fix status: Partial Red Hat: 3 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-770.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00546 46th percentileScored 2026-11-07

Fix Partial fastify (fastify): 5.7.3fastify (npm): 5.7.3Red Hat: 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
fastify	fastify	before 5.7.3	5.7.3	Patch available	CNA
—	fastify (npm)	before 5.7.3	5.7.3	Patch available	GHSA-mrq3-vjjr-p77c

fastify Vendorfastify Affected before 5.7.3 Fixed in 5.7.3 Patch available CNA
fastify (npm) Vendor— Affected before 5.7.3 Fixed in 5.7.3 Patch available GHSA-mrq3-vjjr-p77c

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:fastify:fastify::::::node.js::*	before 5.7.3	Vulnerable	fastify

cpe:2.3:a:fastify:fastify:*:*:*:*:*:node.js:*:* Versions before 5.7.3 Vulnerable ·fastify

Remediation

Fix · CNA fastify (fastify) Fixed in 5.7.3
Fix · GHSA-mrq3-vjjr-p77c fastify (npm) Fixed in 5.7.3 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Enterprise Linux AI (RHEL AI) 3	Affected	No fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)	Affected	No fix yet: Fix deferred
Red Hat OpenShift Dev Spaces	Affected	No fix yet: Fix deferred

Timeline

2026-10-02 Threatist record created from CVE-2026-25224
2026-10-03 Alias added: GHSA-mrq3-vjjr-p77c

References

Patch 1

https://github.com/fastify/fastify/commit/eb11156396f6a5fedaceed0140aed2b7f026be37

Advisory 2

Other 2

TI-2022-18664 Denial of service in Fastify via Content-Type header CVSS 3.1HIGH 7.5
TI-2025-23513 Fastify vulnerable to invalid content-type parsing, which could lead to validation bypass CVSS 3.1HIGH 7.5
TI-2026-58050 fastify vulnerable to request validation bypass via skipped boolean false schemas CVSS 3.1HIGH 7.5
TI-2026-58022 fastify vulnerable to header validation bypass via incomplete schema case normalization CVSS 3.1HIGH 7.5
TI-2026-53284 fastify vulnerable to authentication bypass via malformed URLs reaching encapsulated not-found handlers CVSS 3.1HIGH 7.5
TI-2026-26178 fastify vulnerable to Body Schema Validation Bypass via Leading Space in Content-Type Header CVSS 3.1HIGH 7.5

See all 15 →

Sources

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