Fastify vulnerabilities
We track 25 vulnerabilities in Fastify products across 17 products. 25 are rated high or critical, and none are known to be exploited. The most recent was published on September 4, 2026.
Latest Fastify vulnerabilities
- 7.5 High severity
fastify: Improper Handling of Case Sensitivity
fastify versions before 5.12.2 implement the case-insensitive nature of HTTP header names by lowercasing names in a route's header schema before compiling it, but the transformation is incomplete: it lowercases the properties keys and the root-level required a
- 8.1 High severity
fastify versions before 5.12.2 treat the object resolved by a successful Ajv async validator…
fastify versions before 5.12.2 treat the object resolved by a successful Ajv async validator as the value result protocol used by custom validator compilers. If a request that passes its route schema contains a property named value at the root, fastify replace
- 7.5 High severity
fastify versions before 5.12.2 decide whether to compile a request schema based on JavaScript…
fastify versions before 5.12.2 decide whether to compile a request schema based on JavaScript truthiness, but JSON Schema Draft 7 defines the boolean false as a valid schema that rejects every instance. When an application assigns false to a route's body, quer
- 7.5 High severity
fastify: Authentication Bypass Using an Alternate Path or Channel
fastify versions >= 4.0.0 and before 5.12.2 can route a malformed URL sent under one plugin prefix to the custom not-found handler of a different sibling plugin, and invoke it without the preHandler hook declared for that handler. The internal not-found router
- 7.5 High severity
@fastify/busboy: Loop with Unreachable Exit Condition
@fastify/busboy is a multipart form-data parser. In versions 3.1.0 through 3.2.0, a remote unauthenticated attacker can stall the Node.js event loop by sending a multipart request whose boundary is crafted to a specific length. The vendored streaming search st
- 7.5 High severity
@fastify/busboy: Improper Check for Unusual or Exceptional Conditions
@fastify/busboy is a multipart form-data parser. In versions 1.0.0 through 3.2.0, an attacker who can submit multipart form-data can crash the parser by sending a part header whose name is a prototype-inherited property such as __proto__ or constructor. The in
- 8.6 High severity
@fastify/reply-from: Improper Neutralization of HTTP Headers for Scripting Syntax
@fastify/reply-from v12.6.1 and earlier and @fastify/http-proxy v11.4.3 and earlier process the client's Connection header after the proxy has added its own headers via rewriteRequestHeaders. This allows attackers to retroactively strip proxy-added headers fro
- 9.1 Critical severity
@fastify/express: Interpretation Conflict
Impact@fastify/express v4.0.4 and earlier fails to normalize URLs before passing them to Express middleware when Fastify router normalization options are enabled. This allows complete bypass of path-scoped authentication middleware via duplicate slashes when i
- 9.1 Critical severity
@fastify/express: Interpretation Conflict
@fastify/express v4.0.4 and earlier contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. When a child plugin is registered with a prefix that matches a middleware path, the middlewa
- 7.5 High severity
fastify: Improper Validation of Specified Type of Input
Impact: Fastify applications using schema.body.content for per-content-type body validation can have validation bypassed entirely by prepending a space to the Content-Type header. The body is still parsed correctly but schema validation is skipped. This is a r
- 7.5 High severity
fastify: Interpretation Conflict
Fastify is a fast and low overhead web framework, for Node.js. Prior to version 5.7.2, a validation bypass vulnerability exists in Fastify where request body validation schemas specified by Content-Type can be completely circumvented. By appending a tab charac
- 8.4 High severity
fastify-express: Improper Handling of URL Encoding (Hex Encoding)
The @fastify/express plugin adds full Express compatibility to Fastify. A security vulnerability exists in @fastify/express prior to version 4.0.3 where middleware registered with a specific path prefix can be bypassed using URL-encoded characters (e.g., `/%61
- 8.8 High severity
middie: Improper Handling of URL Encoding (Hex Encoding)
@fastify/middie is the plugin that adds middleware support on steroids to Fastify. A security vulnerability exists in @fastify/middie prior to version 9.1.0 where middleware registered with a specific path prefix can be bypassed using URL-encoded characters (e
- 7.5 High severity
fastify: Improper Validation of Specified Type of Input
Fastify is a fast and low overhead web framework, for Node.js. In versions 5.0.0 to 5.3.0 as well as version 4.29.0, applications that specify different validation strategies for different content types have a possibility to bypass validation by providing a _s
- 7.5 High severity
fastify-multipart: Allocation of Resources Without Limits or Throttling
@fastify/multipart is a Fastify plugin for parsing the multipart content-type. Prior to versions 8.3.1 and 9.0.3, the `saveRequestFiles` function does not delete the uploaded temporary files when user cancels the request. The issue is fixed in versions 8.3.1 a
- 7.4 High severity
@fastify/session is a session plugin for fastify.
@fastify/session is a session plugin for fastify. Requires the @fastify/cookie plugin. When restoring the cookie from the session store, the `expires` field is overriden if the `maxAge` field was set. This means a cookie is never correctly detected as expired
- 7.4 High severity
@festify/secure-session creates a secure stateless cookie session for Fastify.
@festify/secure-session creates a secure stateless cookie session for Fastify. At the end of the request handling, it will encrypt all data in the session with a secret key and attach the ciphertext as a cookie value with the defined cookie name. After that, t
- 7.5 High severity
fastify-reply-from: Inconsistent Interpretation of HTTP Requests
fastify-reply-from is a Fastify plugin to forward the current HTTP request to another server. A reverse proxy server built with `@fastify/reply-from` could misinterpret the incoming body by passing an header `ContentType: application/json ; charset=utf-8`. Thi
- 8.8 High severity
@fastify/oauth2: Cross-Site Request Forgery
All versions of @fastify/oauth2 used a statically generated state parameter at startup time and were used across all requests for all users. The purpose of the Oauth2 state parameter is to prevent Cross-Site-Request-Forgery attacks. As such, it should be uniqu
- 8.1 High severity
fastify-passport: Session Fixation
@fastify/passport is a port of passport authentication library for the Fastify ecosystem. Applications using `@fastify/passport` in affected versions for user authentication, in combination with `@fastify/session` as the underlying session management mechanism
- 7.5 High severity
fastify-multipart: Allocation of Resources Without Limits or Throttling
@fastify/multipart is a Fastify plugin to parse the multipart content-type. Prior to versions 7.4.1 and 6.0.1, @fastify/multipart may experience denial of service due to a number of situations in which an unlimited number of parts are accepted. This includes t
- 8.8 High severity
fastify: Cross-Site Request Forgery
Fastify is a web framework with minimal overhead and plugin architecture. The attacker can use the incorrect `Content-Type` to bypass the `Pre-Flight` checking of `fetch`. `fetch()` requests with Content-Type’s essence as "application/x-www-form-urlencoded", "
- 7.5 High severity
fastify-websocket: Uncaught Exception
@fastify/websocket provides WebSocket support for Fastify. Any application using @fastify/websocket could crash if a specific, malformed packet is sent. All versions of fastify-websocket are also impacted. That module is deprecated, so it will not be patched.
- 7.5 High severity
fastify: Improper Check for Unusual or Exceptional Conditions
fastify is a fast and low overhead web framework, for Node.js. Affected versions of fastify are subject to a denial of service via malicious use of the Content-Type header. An attacker can send an invalid Content-Type header that can cause the application to c
- 7.5 High severity
fastify-bearer-auth: Observable Discrepancy
@fastify/bearer-auth is a Fastify plugin to require bearer Authorization headers. @fastify/bearer-auth prior to versions 7.0.2 and 8.0.1 does not securely use crypto.timingSafeEqual. A malicious attacker could estimate the length of one valid bearer token. Acc