CSRF

Cross-Site Request Forgery (CSRF, sometimes pronounced “sea-surf”, or XSRF) is a type of malicious exploit where unauthorized commands are transmitted from a user that a website trusts.

All core middleware lives in the middleware package:

import "github.com/labstack/echo/v5/middleware"

Usage

e.Use(middleware.CSRF())

How it works

The CSRF middleware supports the Sec-Fetch-Site header as a modern, defense-in-depth approach to CSRF protection, implementing the OWASP-recommended Fetch Metadata API alongside the traditional token-based mechanism.

Modern browsers automatically send the Sec-Fetch-Site header with every request, indicating the relationship between the request origin and the target. The middleware uses this to make a security decision:

• same-origin or none — allowed (exact origin match or direct user navigation)
• same-site — falls back to token validation (for example, subdomain to main domain)
• cross-site — blocked by default with a 403 error for unsafe methods (POST, PUT, DELETE, PATCH)

For browsers that do not send this header (older browsers), the middleware seamlessly falls back to traditional token-based CSRF protection.

Two options tune Sec-Fetch-Site behavior:

• TrustedOrigins []string — allowlist specific origins for cross-site requests (useful for OAuth callbacks, webhooks)
• AllowSecFetchSiteFunc func(c *echo.Context) (bool, error) — custom logic for same-site/cross-site validation

e.Use(middleware.CSRFWithConfig(middleware.CSRFConfig{
  // Allow OAuth callbacks from a trusted provider.
  TrustedOrigins: []string{"https://oauth-provider.com"},

  // Custom validation for same-site/cross-site requests.
  AllowSecFetchSiteFunc: func(c *echo.Context) (bool, error) {
    // Your custom authorization logic here.
    return validateCustomAuth(c), nil
    // return true, err  // blocks the request with an error
    // return true, nil  // allows the request through
    // return false, nil // falls back to legacy token logic
  },
}))

Token-based protection

e := echo.New()
e.Use(middleware.CSRFWithConfig(middleware.CSRFConfig{
  TokenLookup: "header:X-XSRF-TOKEN",
}))

The example above extracts the CSRF token from the X-XSRF-TOKEN request header.

Reading the token from a cookie instead:

middleware.CSRFWithConfig(middleware.CSRFConfig{
  TokenLookup:    "cookie:_csrf",
  CookiePath:     "/",
  CookieDomain:   "example.com",
  CookieSecure:   true,
  CookieHTTPOnly: true,
  CookieSameSite: http.SameSiteStrictMode,
})

Accessing the CSRF token

• Server-side — the token is available from the context under ContextKey and can be passed to the client via a template.
• Client-side — the token can be read from the CSRF cookie.

Configuration

type CSRFConfig struct {
  // Skipper defines a function to skip middleware.
  Skipper Skipper

  // TrustedOrigins permits any request with a `Sec-Fetch-Site` header whose `Origin`
  // header exactly matches one of the listed values. Values should be formatted as
  // the Origin header: "scheme://host[:port]".
  TrustedOrigins []string

  // AllowSecFetchSiteFunc allows custom behaviour for `Sec-Fetch-Site` requests that
  // are about to fail with a CSRF error, to be allowed or replaced with a custom
  // error. Applies to `same-site` and `cross-site` values.
  AllowSecFetchSiteFunc func(c *echo.Context) (bool, error)

  // TokenLength is the length of the generated token.
  // Optional. Default value 32.
  TokenLength uint8

  // TokenLookup is a string in the form "<source>:<name>" or
  // "<source>:<name>,<source>:<name>" used to extract the token from the request.
  // Optional. Default value "header:X-CSRF-Token".
  // Possible values:
  // - "header:<name>" or "header:<name>:<cut-prefix>"
  // - "query:<name>"
  // - "form:<name>"
  // Multiple sources example: "header:X-CSRF-Token,query:csrf".
  TokenLookup string `yaml:"token_lookup"`

  // Generator defines a function to generate the token.
  // Optional. Defaults to randomString(TokenLength).
  Generator func() string

  // ContextKey is the key under which the generated CSRF token is stored in the context.
  // Optional. Default value "csrf".
  ContextKey string

  // CookieName is the name of the CSRF cookie that stores the token.
  // Optional. Default value "_csrf".
  CookieName string

  // CookieDomain is the domain of the CSRF cookie.
  // Optional. Default value none.
  CookieDomain string

  // CookiePath is the path of the CSRF cookie.
  // Optional. Default value none.
  CookiePath string

  // CookieMaxAge is the max age (in seconds) of the CSRF cookie.
  // Optional. Default value 86400 (24h).
  CookieMaxAge int

  // CookieSecure indicates whether the CSRF cookie is secure.
  // Optional. Default value false.
  CookieSecure bool

  // CookieHTTPOnly indicates whether the CSRF cookie is HTTP only.
  // Optional. Default value false.
  CookieHTTPOnly bool

  // CookieSameSite indicates the SameSite mode of the CSRF cookie.
  // Optional. Default value SameSiteDefaultMode.
  CookieSameSite http.SameSite

  // ErrorHandler defines a function that returns custom errors.
  ErrorHandler func(c *echo.Context, err error) error
}

Default configuration

var DefaultCSRFConfig = CSRFConfig{
  Skipper:        DefaultSkipper,
  TokenLength:    32,
  TokenLookup:    "header:" + echo.HeaderXCSRFToken,
  ContextKey:     "csrf",
  CookieName:     "_csrf",
  CookieMaxAge:   86400,
  CookieSameSite: http.SameSiteDefaultMode,
}

Full example

A complete, runnable example is available in the echox cookbook.