PYSEC-2026-4054 Jupyter Server: 5xx request logging leaks token-bearing Referer header values

Summary When a request returns a 500, jupyterserver/log.py logs a small JSON block of request headers. The Referer header was copied into it as-is, so a token in the Referer URL ended up in the logs in plain text. Impact Anyone who can read the server logs can pick tokens out of these 500 entries...

Linux Distros Unpatched Vulnerability : CVE-2026-86049

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Jupyter Server is the backend for Jupyter web applications. Prior to version 2.21.0, the 5xx request logging path in jupyterserver/log.py copies the Referer...

CVE-2026-86049

creationtimestamp| type| source ---|---|--- 2026-09-17 22:35:26+00:00| published-proof-of-concept| https://github.com/jupyter-server/jupyterserver/security/advisories/GHSA-c3mw-737p-c7g2...

Insertion of Sensitive Information into Log File

Overview Affected versions of this package are vulnerable to Insertion of Sensitive Information into Log File via the logrequest function in jupyterserver/log.py, which logs the full Referer header value without sanitization. When a request causes a 500 error, the Referer header - which may conta...

CVE-2026-86049 Jupyter Server: 5xx request logging leaks token-bearing Referer header values

Jupyter Server is the backend for Jupyter web applications. Prior to version 2.21.0, the 5xx request logging path in jupyterserver/log.py copies the Referer header into a JSON header block without applying the token scrubbing used for the request URI. A request that returns HTTP 500 while the...

EUVD-2026-82436

Jupyter Server is the backend for Jupyter web applications. Prior to version 2.21.0, the 5xx request logging path in jupyterserver/log.py copies the Referer header into a JSON header block without applying the token scrubbing used for the request URI. A request that returns HTTP 500 while the...

CVE-2026-86049

Jupyter Server is the backend for Jupyter web applications. Prior to version 2.21.0, the 5xx request logging path in jupyterserver/log.py copies the Referer header into a JSON header block without applying the token scrubbing used for the request URI. A request that returns HTTP 500 while the...

CVE-2026-86049

Jupyter Server is the backend for Jupyter web applications. Prior to version 2.21.0, the 5xx request logging path in jupyterserver/log.py copies the Referer header into a JSON header block without applying the token scrubbing used for the request URI. A request that returns HTTP 500 while the...

Sensitive Information Disclosure

jupyterserver is vulnerable to Sensitive Information Disclosure. The vulnerability is due to improper path validation, which allows unauthenticated attackers to leak the NTLMv2 password hash of the Windows user running the server...

Information Disclosure

jupyterserver is vulnerable to Information Disclosure. An information disclosure flaw exists due to unhandled errors in API requests. While not directly allowing unauthorized access, these errors may leak sensitive path information in responses, potentially revealing sensitive server details to...

Authorization Bypass

jupyterserver is vulnerable to authorization bypass. The vulnerability exists in filemanager.py and handlers.py functions because the hidden files and directories are not properly checked which allows an attacker to bypass and gain access to hidden files and modify sensitive information...

PYSEC-2020-50

The Jupyter Server provides the backend i.e. the core services, APIs, and REST endpoints for Jupyter web applications like Jupyter notebook, JupyterLab, and Voila. In Jupyter Server before version 1.1.1, an open redirect vulnerability could cause the jupyter server to redirect the browser to a...