Overview
Broken Object Level Authorization (BOLA) occurs when an API returns an object to an authenticated user without verifying that the user should access that specific object. The CVE-2026-44374 case describes Backstage modules where unprocessed entity endpoints did not enforce per-object permission checks, allowing any authenticated user to read unprocessed records. This resulted in information disclosure about entities and their ownership, highlighting that authentication alone is insufficient for secure access control.
In Go (Gin) applications, BOLA can manifest when a handler fetches an object by ID and returns it directly without validating ownership or required permissions first. Attackers can enumerate IDs and retrieve resources they do not own by exploiting missing owner checks, mirroring the risk demonstrated by the Backstage CVE.
Remediation involves enforcing per-object authorization in the API layer by validating the authenticated user's identity against the resource owner or a policy decision. For the CVE, patches updated affected Backstage components; in Go, implement explicit owner checks, either in middleware or in the service layer, and constrain database queries accordingly. This guide provides concrete Go (Gin) examples to fix BOLA vulnerabilities while referencing CVE-2026-44374.
Follow-up: add tests to ensure unauthorized access is blocked, and enable auditing of access attempts. Use role-based or attribute-based access controls to prevent broad exposure of objects.
Affected Versions
< 0.6.11 for @backstage/plugin-catalog-backend-module-unprocessed; < 0.0.15 for @backstage/plugin-catalog-unprocessed-entities-common; < 0.2.30 for @backstage/plugin-catalog-unprocessed-entities
Code Fix Example
Go (Gin) API Security Remediation
Vulnerable:
```go
package main
import (
"net/http"
"github.com/gin-gonic/gin"
)
type Entity struct {
ID string `json:"id"`
OwnerID string `json:"owner_id"`
Data string `json:"data"`
}
var store = map[string]Entity{
"a": {ID: "a", OwnerID: "alice", Data: "secretA"},
"b": {ID: "b", OwnerID: "bob", Data: "secretB"},
}
func main() {
r := gin.Default()
r.GET("/entities/:id", func(c *gin.Context) {
id := c.Param("id")
if e, ok := store[id]; ok {
c.JSON(http.StatusOK, e) // No authorization check on ownership
return
}
c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
})
r.Run()
}
```
Fixed:
```go
package main
import (
"net/http"
"strings"
"github.com/gin-gonic/gin"
)
type Entity struct {
ID string `json:"id"`
OwnerID string `json:"owner_id"`
Data string `json:"data"`
}
var store = map[string]Entity{
"a": {ID: "a", OwnerID: "alice", Data: "secretA"},
"b": {ID: "b", OwnerID: "bob", Data: "secretB"},
}
func main() {
r := gin.Default()
r.Use(authMiddleware())
r.GET("/entities/:id", func(c *gin.Context) {
id := c.Param("id")
e, ok := store[id]
if !ok {
c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
return
}
userID := c.GetString("userID")
if e.OwnerID != userID {
// Deny access if the user does not own the resource
c.JSON(http.StatusForbidden, gin.H{"error": "forbidden"})
return
}
c.JSON(http.StatusOK, e)
})
r.Run()
}
func authMiddleware() gin.HandlerFunc {
return func(c *gin.Context) {
// Example: extract user from Authorization: Bearer <token>
// Real implementation should parse and verify JWT and extract userID
auth := c.GetHeader("Authorization")
if strings.HasPrefix(auth, "Bearer ") {
token := strings.TrimPrefix(auth, "Bearer ")
// mock: token is userID for demonstration: "alice" or "bob"
if token == "alice" || token == "bob" {
c.Set("userID", token)
c.Next()
return
}
}
c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
}
}
```