CVE-2026-86049 Jupyter Server - Information Disclosure

Jupyter Server < 2.21.0 contains an information disclosure vulnerability caused by improper token scrubbing of the Referer header in 5xx request logging, letting attackers with log access recover tokens, exploit requires log access.

CVSS base score 7.1 /10
High
CISA KEV
Not listed
Public exploit
None known
EPSS
0.42% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Information Disclosure
Impact
Information Disclosure
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
Published
17 September 2026
Updated
15 October 2026
Weakness
CWE-532

Vendor fix

Update to version 2.21.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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