Authorization Bypass Through User-Controlled Key
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
Retrieval of a user record usually occurs in the system based on some key value. When a value that is directly specified by the user is used to look up that record, the key value can be modified to access records belonging to other users.
Prevalence
High
Frequently exploited
Impact
Critical
1 critical-severity rules
Prevention
Documented
8 fix examples
2 Prevention
2 Prevention
How to fix this vulnerability
Prevention strategies for Authorization Bypass via User Key based on 8 Shoulder detection rules.
Horizontal Privilege Escalation
HIGH
Validate resource ownership before allowing modifications using user-supplied IDs
func updateProfile(c *gin.Context) { profileID := c.Param("id") - db.Model(&Profile{}).Where("id = ?", profileID).Updates(data) + userID := c.GetString("user_id") + var profile Profile + db.First(&profile, profileID) + if profile.UserID != userID { + c.JSON(403, gin.H{"error": "unauthorized"}) + return + } + db.Model(&profile).Updates(data) }
Insecure Direct Object Reference (IDOR)
HIGH
Validate resource ownership before database access using user-supplied IDs
func getUser(c *gin.Context) { - userID := c.Param("id") - var user User - db.First(&user, userID) + requestedID := c.Param("id") + currentID := c.GetString("user_id") + if requestedID != currentID { + c.JSON(403, gin.H{"error": "unauthorized"}) + return + } + var user User + db.First(&user, requestedID) c.JSON(200, user) }
Potential IDOR - Generic Data Access
MEDIUM
Verify resource ownership before returning data accessed by user-supplied identifiers
func getOrder(c *gin.Context) { orderID := c.Param("id") - order := orders[orderID] + currentUserID := c.GetString("user_id") + order := orders[orderID] + if order.UserID != currentUserID { + c.JSON(403, gin.H{"error": "Forbidden"}) + return + } c.JSON(200, order) }
JavaScript
View all JavaScript details →
Horizontal Privilege Escalation
CRITICAL
Filter queries by authenticated user ID to verify resource ownership
app.get('/api/profile/:userId', async (req, res) => { - const profile = await User.findOne({ where: { id: req.params.userId } }); + const profile = await User.findOne({ + where: { id: req.params.userId, userId: req.user.id } + }); + if (!profile) return res.status(403).json({ error: 'Forbidden' }); res.json(profile); });
Insecure Direct Object Reference (IDOR)
HIGH
Include userId in database queries to verify resource ownership before access
app.get('/api/orders/:id', async (req, res) => { - const order = await Order.findByPk(req.params.id); + const order = await Order.findOne({ + where: { id: req.params.id, userId: req.user.id } + }); + if (!order) return res.status(404).json({ error: 'Not found' }); res.json(order); });
Potential IDOR - Generic Data Access
MEDIUM
Verify resource ownership before returning data by checking it belongs to the authenticated user
app.get('/api/orders/:id', (req, res) => { const order = orderRepo.findById(req.params.id); + if (order.userId !== req.user.id) { + return res.status(403).json({ error: 'Forbidden' }); + } res.json(order); });
Python
View all Python details →
Insecure Direct Object Reference (IDOR)
HIGH
Include the authenticated user as a filter condition in all ORM queries that use user-supplied IDs
- def get_document(request, doc_id): - requested_id = request.GET.get('id') - document = Document.objects.get(id=requested_id) + from django.contrib.auth.decorators import login_required + + @login_required + def get_document(request, doc_id): + requested_id = request.GET.get('id') + document = Document.objects.get( + id=requested_id, + owner=request.user + ) return JsonResponse(document.to_dict())
3 Detection
3 Detection
Find vulnerabilities in your code
Use Shoulder to scan your codebase for Authorization Bypass Through User-Controlled Key patterns. 8 rules.
# Scan with Shoulder CLI npx @shoulderdev/cli trust --cwe=639 # Or scan entire project npx @shoulderdev/cli trust .
Detection Rules (8)
🐹
Go
3 rules
Horizontal Privilege Escalation
HIGH
Detects horizontal privilege escalation where users can access or modify other users' resources.
Insecure Direct Object Reference (IDOR)
HIGH
Detects IDOR vulnerabilities where user-supplied IDs access resources without authorization checks.
Potential IDOR - Generic Data Access
MEDIUM
Detects route parameters flowing to data access without visible ownership verification.
🟨
Javascript
3 rules
Horizontal Privilege Escalation
CRITICAL
Detects when user-controlled input is used to access resources belonging to other users
at the same privilege level without verifying ownership.
Insecure Direct Object Reference (IDOR)
HIGH
Detects when user-controlled input (from URL parameters, query strings, or request body)
is used directly to access database records without verifying that the authenticated
user has permission to access that specific resource.
IDOR vulnerabilities allow attackers to access, modify, or delete resources belonging
to other users by manipulating identifiers in requests.
Potential IDOR - Generic Data Access
MEDIUM
Detects endpoints where route parameters flow to generic data access patterns
(Map.get, object property access, cache lookups, custom repositories) without
visible ownership verification in the function.
This rule catches patterns that ORM-specific detection misses, but requires
human verification that authorization is not enforced elsewhere (middleware,
decorators, API gateway, etc.).
**This is a "potential" finding - verify authorization exists somewhere.**
🔷
Typescript
3 rules
Horizontal Privilege Escalation
CRITICAL
Detects when user-controlled input is used to access resources belonging to other users
at the same privilege level without verifying ownership.
Insecure Direct Object Reference (IDOR)
HIGH
Detects when user-controlled input (from URL parameters, query strings, or request body)
is used directly to access database records without verifying that the authenticated
user has permission to access that specific resource.
IDOR vulnerabilities allow attackers to access, modify, or delete resources belonging
to other users by manipulating identifiers in requests.
Potential IDOR - Generic Data Access
MEDIUM
Detects endpoints where route parameters flow to generic data access patterns
(Map.get, object property access, cache lookups, custom repositories) without
visible ownership verification in the function.
This rule catches patterns that ORM-specific detection misses, but requires
human verification that authorization is not enforced elsewhere (middleware,
decorators, API gateway, etc.).
**This is a "potential" finding - verify authorization exists somewhere.**
4 Warning Signs
4 Warning Signs
What to watch for in code reviews
These patterns indicate potential Authorization Bypass Through User-Controlled Key vulnerabilities. Look for these during code reviews and security audits.
User can access other users' resources without authorization
go-horizontal-privilege-escalation
horizontal privilege escalation where users can access or modify other users' resources
go-horizontal-privilege-escalation
User-supplied ID used to access resource without authorization check
go-idor
IDOR vulnerabilities where user-supplied IDs access resources without authorization checks
go-idor
when user-controlled input (from URL parameters, query strings, or request body)
is used directly to
javascript-idor
database object access using user-provided IDs without ownership
verification
python-idor
route parameters flowing to data access without visible ownership verification
go-idor-generic
endpoints where route parameters flow to generic data access patterns
(Map
javascript-idor-generic
Scan your codebase for Authorization Bypass Through User-Controlled Key
Shoulder CLI finds vulnerable patterns across your entire codebase.