CVE-2026-86049High· 7.1▾ TwilightJupyter Server is the backend for Jupyter web applications. Prior to version 2.21.0, the 5xx request logging path in jupyter_server/log.py copies the Referer header into a JSON header block without applying the token scrubbing used for t…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 39.1 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Sep 18.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.2%
Last analysed / modified upstream
0.2% → 0.4%
Jupyter Server is the backend for Jupyter web applications. Prior to version 2.21.0, the 5xx request logging path in jupyter_server/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 Referer contains a token-bearing URL can therefore write that token to server logs in plaintext. An attacker who can read those logs can recover the token and use the affected user's Jupyter Server permissions. This issue is fixed in version 2.21.0.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
jupyter_server <= 2.20.0Patched in:
jupyter_server 2.21.0Source: https://github.com/advisories/GHSA-c3mw-737p-c7g2
Connected by shared product, vendor, weakness, or advisory.
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