{"id":"PYSEC-2026-300","summary":"Browser Use allows bypassing `allowed_domains` by putting a decoy domain in http auth username portion of a URL","details":"### Summary  \nDuring a manual source code review, [**ARIMLABS.AI**](https://arimlabs.ai) researchers identified that the `browser_use` module includes an embedded whitelist functionality to restrict URLs that can be visited. This restriction is enforced during agent initialization. However, it was discovered that these measures can be bypassed, leading to severe security implications.  \n\n### Details  \n**File:** `browser_use/browser/context.py`  \n\nThe `BrowserContextConfig` class defines an `allowed_domains` list, which is intended to limit accessible domains. This list is checked in the `_is_url_allowed()` method before navigation:\n\n```python\n@dataclass\n class BrowserContextConfig:\n    \"\"\"\n    [STRIPPED]\n    \"\"\"\n    cookies_file: str | None = None\n    minimum_wait_page_load_time: float = 0.5\n    wait_for_network_idle_page_load_time: float = 1\n    maximum_wait_page_load_time: float = 5\n    wait_between_actions: float = 1\n\n    disable_security: bool = True\n\n    browser_window_size: BrowserContextWindowSize = field(default_factory=lambda: {'width': 1280, 'height': 1100})\n    no_viewport: Optional[bool] = None\n\n    save_recording_path: str | None = None\n    save_downloads_path: str | None = None\n    trace_path: str | None = None\n    locale: str | None = None\n    user_agent: str = (\n        'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.102 Safari/537.36'\n    )\n\n    highlight_elements: bool = True\n    viewport_expansion: int = 500\n    allowed_domains: list[str] | None = None\n    include_dynamic_attributes: bool = True\n\n    _force_keep_context_alive: bool = False\n```\nThe _is_url_allowed() method is responsible for checking whether a given URL is permitted:\n```python\ndef _is_url_allowed(self, url: str) -\u003e bool:\n    \"\"\"Check if a URL is allowed based on the whitelist configuration.\"\"\"\n    if not self.config.allowed_domains:\n        return True\n\n    try:\n        from urllib.parse import urlparse\n\n        parsed_url = urlparse(url)\n        domain = parsed_url.netloc.lower()\n\n        # Remove port number if present\n        if ':' in domain:\n            domain = domain.split(':')[0]\n\n        # Check if domain matches any allowed domain pattern\n        return any(\n            domain == allowed_domain.lower() or domain.endswith('.' + allowed_domain.lower())\n            for allowed_domain in self.config.allowed_domains\n        )\n    except Exception as e:\n        logger.error(f'Error checking URL allowlist: {str(e)}')\n        return False\n```\nThe core issue stems from the line `domain = domain.split(':')[0]`, which allows an attacker to manipulate basic authentication credentials by providing a username:password pair. By replacing the username with a whitelisted domain, the check can be bypassed, even though the actual domain remains different.\n### Proof of Concept (PoC)\n\nSet allowed_domains to ['example.com'] and use the following URL:\n\nhttps://example.com:pass@localhost:8080\n\nThis allows bypassing all whitelist controls and accessing restricted internal services.\n### Impact\n\n- Affected all users relying on this functionality for security.\n- Potential for unauthorized enumeration of localhost services and internal networks.\n- Ability to bypass domain whitelisting, leading to unauthorized browsing.","aliases":["CVE-2025-47241","GHSA-x39x-9qw5-ghrf"],"modified":"2026-07-13T16:15:15.786385452Z","published":"2026-06-29T11:50:36.064223Z","references":[{"type":"WEB","url":"https://github.com/browser-use/browser-use/security/advisories/GHSA-x39x-9qw5-ghrf"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-47241"},{"type":"WEB","url":"https://github.com/browser-use/browser-use/pull/1561"},{"type":"PACKAGE","url":"https://github.com/browser-use/browser-use"},{"type":"WEB","url":"https://github.com/browser-use/browser-use/releases/tag/0.1.45"},{"type":"PACKAGE","url":"https://pypi.org/project/browser-use"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-x39x-9qw5-ghrf"}],"affected":[{"package":{"name":"browser-use","ecosystem":"PyPI","purl":"pkg:pypi/browser-use"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.1.45"}]}],"versions":["0.1.0","0.1.1","0.1.10","0.1.11","0.1.12","0.1.13","0.1.14","0.1.15","0.1.16","0.1.17","0.1.18","0.1.19","0.1.20","0.1.21","0.1.22","0.1.23","0.1.24","0.1.25","0.1.26","0.1.27","0.1.28","0.1.29","0.1.3","0.1.30","0.1.31","0.1.32","0.1.33","0.1.34","0.1.35","0.1.36","0.1.37","0.1.38","0.1.39","0.1.4","0.1.40","0.1.41","0.1.42","0.1.43","0.1.5","0.1.6","0.1.7","0.1.8"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/browser-use/PYSEC-2026-300.yaml"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L"}]}