SB20260505104 - Multiple vulnerabilities in Jupyter Server

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Main Vulnerability Database SB20260505104

SB20260505104 - Multiple vulnerabilities in Jupyter Server

Published: May 5, 2026 Updated: September 3, 2026

Security Bulletin ID SB20260505104
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 4
Exploitation vector Remote access
Highest impact Information disclosure

Breakdown by Severity

Medium 50% Low 50%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 4 vulnerabilities.


1) Regular Expression without Anchors (CVE-ID: CVE-2026-40110)

CWE-ID: CWE-777 - Regular Expression without Anchors

CVSSv4: 7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to disclose sensitive information and modify data.

The vulnerability exists due to regular expression without anchors in the allow_origin_pat Origin header validation when validating cross-origin requests. A remote attacker can use a controlled domain that prefixes a trusted origin to bypass validation and disclose sensitive information and modify data.

User interaction is required.


2) Insufficient Session Expiration (CVE-ID: CVE-2026-40934)

CWE-ID: CWE-613 - Insufficient Session Expiration

CVSSv4: 7.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote user to maintain indefinite authenticated access.

The vulnerability exists due to insufficient session expiration in the authentication cookie handling when reusing previously issued authentication cookies after a password reset and server restart. A remote user can reuse a stolen or compromised authentication cookie to maintain indefinite authenticated access.

The issue affects deployments using password authentication.


3) Open redirect (CVE-ID: CVE-2025-61669)

CWE-ID: CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to redirect users to arbitrary external domains.

The vulnerability exists due to url redirection to an untrusted site in LoginFormHandler._redirect_safe() when processing the next query parameter. A remote attacker can supply a crafted next parameter to redirect users to arbitrary external domains.

User interaction is required for a victim to follow the crafted login URL.


4) Path traversal (CVE-ID: CVE-2026-35397)

CWE-ID: CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSSv4: 7.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N]


The vulnerability allows a remote user to disclose sensitive information and modify data outside the intended directory scope.

The vulnerability exists due to path traversal in jupyter-server REST API when handling crafted path inputs relative to the root_dir. A remote user can send a specially crafted request to disclose sensitive information and modify data outside the intended directory scope.

Access is limited to a subset of directories that are siblings of the configured root_dir.


Remediation

Install update from vendor's website.

References