CVE-2021-29624Network attack vector

CSRF bypass via unbound double-submit cookies

Published May 19, 2021 · Updated Aug 3, 2024

CSRF protection bypass in Fastify @fastify/csrf-protection before 3.1.0 allows remote attackers to submit forged requests. The double-submit flow accepts a cookie scoped from another subdomain without binding the CSRF token to user-specific information. Exploitation requires attacker-controlled sibling subdomains and victim interaction, enabling unauthorized actions with the victim's session.

CVSS severity6.5
Medium
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CSRF protection bypass in Fastify @fastify/csrf-protection before 3.1.0 allows remote attackers to submit forged requests. The double-submit flow accepts a cookie scoped from another subdomain without binding the CSRF token to user-specific information. Exploitation requires attacker-controlled sibling subdomains and victim interaction, enabling unauthorized actions with the victim's session.

The record

CVE
CVE-2021-29624
Published
May 19, 2021
Updated
Aug 3, 2024
Vendor
Fastify
Product
@fastify/csrf-protection
Classifications
CWE-352, CWE-565
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fastify · @fastify/csrf-protectionversion=< 3.1.0

Published CVSS scores

6.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
CWE-565Reliance on Cookies without Validation and Integrity Checking

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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