v4.15.4

Security

Fixes GHSA-vfp3-v2gw-7wfq: an encoded path separator (%2F or %5C) in a static file URL could bypass route-level middleware (e.g. authentication on a sibling route) and disclose static files. Both StaticDirectoryHandler (used by Static/StaticFS) and the Static middleware are affected. Backport of the v5 fix (#3016, released in v5.2.1). Thanks to @a-tt-om and @oran-gugu for reporting.

---

Make serving static file releated methods and middleware not unescape path by default - so how the way Router interprets paths and Static methods/middleware is consistent.

Given following situation:

// 0.
// given folder structure:
// private.txt
// public/
// public/index.html
// public/text.txt
// public/admin/private.txt

// 1. share `public/` folder contents from the server root. This folder actually contains subfolder `admin` which
// contents we want to forbid from downloading
e.Static("/", "public")

// 2. naively assume that everything under /admin folder is now forbidden
e.GET("/admin/*", func(c *Context) error {
    return ErrForbidden
})

Then requests to /admin%2fprivate.txt would not be matched to GET /admin/* route (routing does not look unescaped path) and static file serving will use unescaped path to serve the file.

Note: this way of "guarding" subfolders will never work for for paths like /assets/../admin%2fprivate.txt which will path.Clean("/assets/../admin%2fprivate.txt") to /admin/private.txt and are servable if static file serving is configured to unescape paths.

If you want to guard routes - use middlewares on Static* methods and before Static middleware.

Breaking change / migration: If you serve files whose names contain URL-encoded characters (e.g., /hello%20world.txt → hello world.txt), you must now opt in:

	e := echo.New()
	e.EnablePathUnescapingStaticFiles = true  // <-- enable old behavior
	e.Static("/", "public")

for static middleware

	e.Use(middleware.StaticWithConfig(middleware.StaticConfig{
		EnablePathUnescaping: true, // <-- enable old behavior
	}))

Full Changelog: v4.15.3...v4.15.4