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**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** joserfc versions 1.3.4 through 1.6.5 **Description** joserfc is a Python library implementing JSON Object Signing and Encryption (JOSE) standards. The library fails to apply the `JWSRegistry.max payload length` limit when processing RFC7797 `b64=false` JWS payloads. While standard JWS compact and flattened JSON paths correctly reject oversized payloads with an ExceededSizeError, the RFC7797 unencoded payload paths bypass this check. This allows the successful deserialization of payloads exceeding the configured size limit, which can lead to resource exhaustion and pose an availability risk for applications accepting lower-trust JWS values. **Recommendations** Update to version 1.6.7.

**Name of the Vulnerable Software and Affected Versions** Mako versions prior to 1.3.11 **Description** Mako is a template library written in Python. The `get template()` function within `TemplateLookup` is susceptible to path traversal when a URI begins with //. This occurs due to an inconsistency between two slash-stripping implementations. If an application passes untrusted input directly to `get template()`, any file readable by the process can be returned as rendered template content. **Recommendations** Update to version 1.3.11.