Memory Leak in Buffalo with Basic Auth

A memory leak in a Buffalo application that uses HTTP Basic Auth can occur when request-scoped objects are retained beyond the request lifecycle, often because authenticated handlers or middleware keep references to large request or response objects. With Basic Auth, each request carries credentials in the Authorization header, and if the application allocates buffers, decodes credentials, or binds them to long-lived structures (for example, storing parsed user identity in a global cache without cleanup), the associated memory is not released promptly. This pattern is observable in handlers that decode base64 credentials on every request but fail to discard temporary objects, leading to gradual heap growth under sustained load.

Buffalo's request lifecycle ties closely to middleware chains; if Basic Auth validation logic creates objects (e.g., user session representations or per-request context) and these are inadvertently attached to a global store or a long-running goroutine, the garbage collector cannot reclaim them. For instance, capturing the request’s Basic Auth user in a package-level map keyed by request identifiers without eviction will accumulate entries, increasing resident memory over time. This is especially relevant when the endpoint also performs operations that allocate sizable buffers—such as processing uploaded files or constructing large JSON responses—amplifying the leak’s impact on memory consumption.

An unauthenticated scan using middleBrick can surface indicators such as steady memory growth across repeated authenticated requests or elevated process memory in runtime metrics, flagging the endpoint in findings like Unsafe Consumption or Input Validation. Because middleBrick tests the unauthenticated attack surface, it may detect endpoints that accept Basic Auth but do not enforce strict resource boundaries, correlating observed behavior with patterns known to cause retention. Remediation focuses on ensuring that per-request objects are not stored beyond their scope and that buffers tied to authenticated operations are released deterministically within the request handler.

To mitigate memory leaks with Basic Auth in Buffalo, ensure that credentials are decoded, validated, and used without persisting request-specific data in long-lived structures. Prefer extracting the username and password within the handler, creating only short-lived variables, and avoiding assignment to global or package-level containers. Use request context for passing validated identity, and clear or limit any caches that might retain references beyond the request.

Example: Safe Basic Auth Handler

package actions

import (
    "encoding/base64"
    "strings"

    "github.com/gobuffalo/buffalo"
    "github.com/gobuffalo/packr/v2"
)

func AuthenticatedUser(c buffalo.Context) error {
    auth := c.Request().Header.Get("Authorization")
    if auth == "" {
        return c.Render(401, r.JSON(map[string]string{"error": "unauthorized"}))
    }
    const prefix = "Basic "
    if !strings.HasPrefix(auth, prefix) {
        return c.Render(401, r.JSON(map[string]string{"error": "unauthorized"}))
    }
    payload, err := base64.StdEncoding.DecodeString(auth[len(prefix):])
    if err != nil {
        return c.Render(401, r.JSON(map[string]string{"error": "unauthorized"}))
    }
    parts := strings.SplitN(string(payload), ":", 2)
    if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
        return c.Render(401, r.JSON(map[string]string{"error": "unauthorized"}))
    }
    username, password := parts[0], parts[1]
    // Use username/password for validation, e.g., check against a data store
    // Do NOT store username in a global map or long-lived cache
    c.Set("current_user", username) // context-scoped, request-bound
    return c.Next()
}

Middleware to Attach User to Context

package middleware

import (
    "net/http"
    "strings"

    "github.com/gobuffalo/buffalo"
)

func BasicAuth(next buffalo.HandlerFunc) buffalo.HandlerFunc {
    return func(c buffalo.Context) error {
        auth := c.Request().Header.Get("Authorization")
        if auth == "" {
            return c.Render(http.StatusUnauthorized, r.JSON(map[string]string{"error": "unauthorized"}))
        }
        const prefix = "Basic "
        if !strings.HasPrefix(auth, prefix) {
            return c.Render(http.StatusUnauthorized, r.JSON(map[string]string{"error": "unauthorized"}))
        }
        payload, err := base64.StdEncoding.DecodeString(auth[len(prefix):])
        if err != nil {
            return c.Render(http.StatusUnauthorized, r.JSON(map[string]string{"error": "unauthorized"}))
        }
        parts := strings.SplitN(string(payload), ":", 2)
        if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
            return c.Render(http.StatusUnauthorized, r.JSON(map[string]string{"error": "unauthorized"}))
        }
        c.Set("current_user", parts[0])
        return next(c)
    }
}

In the above, the handler and middleware keep credentials scoped to the request context, avoiding global retention. Ensure that any caches or session stores have size limits and eviction policies to prevent unbounded growth. With middleBrick, you can validate remediation by rescanning the endpoint; the CLI allows repeat scans from the terminal with middlebrick scan <url>, while the GitHub Action can enforce security thresholds in CI/CD pipelines.