Y011D4

**Name of the Vulnerable Software and Affected Versions** jupyter-server versions prior to 2.20.0 **Description** The nbconvert HTTP handlers render user-authored notebook HTML under the Jupyter origin without a sandbox directive in their Content-Security-Policy (CSP), which is a security layer that helps detect and mitigate certain types of attacks. Combined with the default non-sanitizing behavior of `nbconvert.HTMLExporter`, a notebook containing an HTML payload in a display data output can trigger stored Cross-Site Scripting (XSS). This allows an authenticated attacker to achieve full session takeover, token exfiltration to another domain, and kernel Remote Code Execution (RCE). The issue is triggered when a victim navigates to the endpoint "/nbconvert/html/<path>". **Recommendations** Update to version 2.20.0. As a temporary workaround, add the following configuration to `jupyter server config.py` to implement the sandbox directive: import jupyter server.nbconvert.handlers as nb def csp(self): return super(type(self), self).content security policy + "; sandbox allow-scripts" nb.NbconvertFileHandler.content security policy = property( csp) nb.NbconvertPostHandler.content security policy = property( csp)

**Name of the Vulnerable Software and Affected Versions** Authlib versions prior to 1.6.12 Authlib versions prior to 1.7.1 **Description** An unauthenticated open redirect exists in the authorization endpoint of the `OpenIDImplicitGrant` and `OpenIDHybridGrant` components. A remote attacker can cause the authorization server to issue an HTTP 302 redirect to an arbitrary, attacker-chosen URL by submitting an authorization request that omits the `openid` scope. This occurs because the `validate authorization request()` function in both grants performs the scope check before validating the `redirect uri` against the registered client URIs. Consequently, the `InvalidScopeError` is triggered using an unvalidated `redirect uri` variable, which the `OAuth2Error. call ` function then processes as a redirect location. **Recommendations** Update to version 1.6.12 or 1.7.1. As a temporary mitigation, unregister `OpenIDImplicitGrant` and `OpenIDHybridGrant` if Implicit and Hybrid flows are not required.