The CSRF protection enforced by the @fastify/csrf-protection library in combination with @fastify/cookie can be bypassed from network and same-site attackers under certain conditions.
@fastify/csrf-protection supports an optional userInfo parameter that binds the CSRF token to the user. This parameter has been introduced to prevent cookie-tossing attacks as a fix for CVE-2021-29624. Whenever userInfo parameter is missing, or its value can be predicted for the target user account, network and same-site attackers can 1. fixate a _csrf cookie in the victim's browser, and 2. forge CSRF tokens that are valid for the victim's session. This allows attackers to bypass the CSRF protection mechanism.
As a fix, @fastify/csrf-protection starting from version 6.3.0 (and v4.1.0) includes a server-defined secret hmacKey that cryptographically binds the CSRF token to the value of the _csrf cookie and the userInfo parameter, making tokens non-spoofable by attackers. This protection is effective as long as the userInfo parameter is unique for each user.
This is patched in version 6.3.0 and v4.1.0.
As a workaround, developers can use a random, non-predictable userInfo parameter for each user.
| Score | Percentile |
|---|---|
| 0.11% | 30.22% |
| Base score | Version | Severity | Vector |
|---|---|---|---|
| 5.3 | 3.1 | — |
|
| Type | Value |
|---|---|
| GHSA | GHSA-qrgf-9gpc-vrxw ↗ |
| CVE | CVE-2023-27495 ↗ |
| CWE id | Name |
|---|---|
| CWE-352 | Cross-Site Request Forgery (CSRF) |
Vulnerable version ranges and first patched releases as published by GitHub.
| Ecosystem | Package | Vulnerable range | First patched | Vulnerable functions |
|---|---|---|---|---|
| npm | @fastify/csrf-protection | < 4.1.0 | 4.1.0 | — |
| npm | @fastify/csrf-protection | >= 5.0.0, < 6.3.0 | 6.3.0 | — |