GHSA-qrgf-9gpc-vrxw Bypass of CSRF protection in the presence of predictable userInfo

• npm @fastify/csrf-protection: < 4.1.0 → fixed in 4.1.0 • npm @fastify/csrf-protection: >= 5.0.0, < 6.3.0 → fixed in 6.3.0

Description 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. Patches This is patched in version 6.3.0 and v4.1.0. Workarounds As a workaround, developers can use a random, non-predictable `userInfo` parameter for each user. Credits • Pedro Adão (@pedromigueladao), Instituto Superior Técnico, University of Lisbon • Marco Squarcina (@lavish), Security & Privacy Research Unit, TU Wien