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Fastify CVE-2021-29624

MEDIUM
Reliance on Cookies without Validation and Integrity Checking (CWE-565)
2021-05-19 security-advisories@github.com
6.5
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A08:2025 - Software or Data Integrity Failures
ASVS 5.0
V3 - Web Frontend Security Cookie integrity validation
Impact

CVSS score of 6.5 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, user interaction required.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the medium-severity affected system.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.8% exploitation probability (EPSS)

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AnalysisAI

fastify-csrf is an open-source plugin helps developers protect their Fastify server against CSRF attacks. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affected Packages

npm fastify-csrf fix: 3.1.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in npm

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-565. fastify-csrf is an open-source plugin helps developers protect their Fastify server against CSRF attacks. Versions of fastify-csrf prior to 3.1.0 have a "double submit" mechanism using cookies with an application deployed across multiple subdomains, e.g. "heroku"-style platform as a service. Version 3.1.0 of the fastify-csrf fixes it. the vulnerability. The user of the module would need to supply a userInfo when generating the CSRF token to fully implement the protection on their end. This is needed only for applications hosted on different subdomains. Affected products include: Fastify Fastify-Csrf. Version information: prior to 3.1.0.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

DescriptionNVD

fastify-csrf is an open-source plugin helps developers protect their Fastify server against CSRF attacks. Versions of fastify-csrf prior to 3.1.0 have a "double submit" mechanism using cookies with an application deployed across multiple subdomains, e.g. "heroku"-style platform as a service. Version 3.1.0 of the fastify-csrf fixes it. the vulnerability. The user of the module would need to supply a userInfo when generating the CSRF token to fully implement the protection on their end. This is needed only for applications hosted on different subdomains.

Threat Intelligence Overview

EPSS Score
0.8%
Top 47% exploitable
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.8%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

33
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +32
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Request Forgery exploits the automatic credential inclusion behavior of web browsers.

Affected Products (CPE)NVD

cpe:2.3:a:fastify:fastify-csrf:*:*:*:*:*:node.js:*:*
CVE-2023-31999 HIGH POC
8.8 Jul 04

All versions of @fastify/oauth2 used a statically generated state parameter at startup time and were used across all req

CVE-2021-22964 HIGH POC
8.8 Oct 14

A redirect vulnerability in the `fastify-static` module version >= 4.2.4 and < 4.4.1 allows remote attackers to redirect

CVE-2025-32442 HIGH POC
7.5 Apr 18

Fastify is a fast and low overhead web framework, for Node.js. Rated high severity (CVSS 7.5), this vulnerability is rem

CVE-2020-8136 HIGH POC
7.5 Mar 20

Prototype pollution vulnerability in fastify-multipart < 1.0.5 allows an attacker to crash fastify applications parsing

CVE-2018-3711 HIGH POC
7.5 Jun 07

Fastify node module before 0.38.0 is vulnerable to a denial-of-service attack by sending a request with "Content-Type: a

CVE-2020-8192 MEDIUM POC
6.5 Jul 30

A denial of service vulnerability exists in Fastify v2.14.1 and v3.0.0-rc.4 that allows a malicious user to trigger reso

CVE-2021-22963 MEDIUM POC
6.1 Oct 14

A redirect vulnerability in the fastify-static module version < 4.2.4 allows remote attackers to redirect users to arbit

CVE-2026-6556 CRITICAL
9.1 Jun 30

Authorization bypass in the @fastify/express middleware-compatibility plugin (versions 4.0.6 and earlier) lets unauthent

CVE-2026-33808 CRITICAL
9.1 Apr 15

Authentication bypass in @fastify/express v4.0.4 and earlier allows remote unauthenticated attackers to access protected

CVE-2026-33807 CRITICAL
9.1 Apr 15

Middleware bypass in Fastify Express plugin (fastify/express) allows complete circumvention of authentication, authoriza

CVE-2022-41919 HIGH
8.8 Nov 22

Fastify is a web framework with minimal overhead and plugin architecture. Rated high severity (CVSS 8.8), this vulnerabi

CVE-2026-2880 HIGH
8.2 Feb 27

Authentication and authorization bypass in @fastify/middie (Node.js middleware library for Fastify) allows remote unauth

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