CVE Intelligence
High Access control

CVE-2026-114135 — Jupyter Server: Gateway WebSocket handler bypasses kernel execute authorization

Jupyter Server is the backend for Jupyter web applications. From 2.0.0 until 2.6.0, enabling GatewayClient.url replaced the normal KernelWebsocketHandler with WebSocketChannelsHandler, which authenticated the user but did not call authorizer.is_authorized(...) for the execute action on the kernels resource. A restricted authenticated user could therefore open an upstream kernel channel and obtain kernel execution despite the configured Authorizer denying that action, exposing data and credentials available to the kernel and permitting modification or disruption of the kernel environment. The default gateway configuration is fixed in version 2.6.0. In 2.6.0 and later, the same authorization bypass remains possible when a deployment manually registers the deprecated jupyter_server.gateway.handlers module, because its handler still omits the configured kernel-execute authorization decision.

Published Oct 21, 2026 · Updated Oct 27, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: GitHub_M

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.5% (30-day exploitation probability)+6
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.48%
ahead of 42% of scored CVEs · Oct 27, 2026
Affects
Jupyter-server
Jupyter Server and 1 more
CVSS base
8.8
High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Pip Jupyter-server: fixed in version 2.6.0 — github.com (GitHub Security Advisories)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Jupyter-server Jupyter Server, Pip Jupyter-server).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Search available logs for exploit probes matching the vulnerability class (access control), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Jupyter-server Jupyter Server version >= 2.0.0, < 2.6.0 Vulnerable CVE Program (cve.org) e CISA ADP
Pip Jupyter-server ≥ 2.0.0 and < 2.6.0 Vulnerable GitHub Security Advisories

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.8 CVSS 3.1 High 2.8 5.9 security-advisories@github.com via NIST National Vulnerability Database
8.8 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
8.8 CVSS 3.1 High — — GitHub_M via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: security-advisories@github.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-862 · Missing Authorization

Other CVEs with this weakness →

EPSS over time FIRST

Oct 22, 2026 → Oct 27, 2026 · 6 reading(s) · max 0.48%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Audit administrative actions and access to resources outside each user’s normal pattern.
web/proxy/WAF logsnetwork IDS/IPSauthentication logsapplication logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • SSVC assessment updated
    Oct 27, 2026 · CVE Program (cve.org) e CISA ADP
  • Fix documented
    Oct 22, 2026 · GitHub Security Advisories
  • Affected products added · pip/jupyter-server
    Oct 22, 2026 · GitHub Security Advisories
  • Source status changed · Received → Awaiting Analysis
    Oct 22, 2026 · NIST National Vulnerability Database
  • Affected products added · jupyter-server/jupyter server
    Oct 21, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 21, 2026
  • CVSS changed · 8.8
    Oct 21, 2026 · NIST National Vulnerability Database
  • Source status changed · → Received
    Oct 21, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 21, 2026 · Alertas do Telegram
  • CVE published
    Oct 21, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 21, 2026 – Oct 22, 2026
  • 1× Official description updated · Oct 21, 2026 – Oct 21, 2026

References

6 on the record

Elsewhere on this site

Jupyter-server
every CVE for this vendor
Access control
same class
CWE-862
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-86049 Jupyter Server: 5xx request logging leaks token-bearing Referer header values Sep 17, 2026
  • CVE-2026-44727 Jupyter Server: Stored XSS in `NbconvertFileHandler` / `NbconvertPostHandler` via missing `sandbox` CSP Jun 22, 2026
  • CVE-2026-40110 jupyter-server CORS origin validation bypass via unanchored regex in allow_origin_pat May 5, 2026
  • CVE-2026-40934 jupyter-server authentication cookies remain valid after password reset due to static cookie secret May 5, 2026
  • CVE-2026-35397 jupyter-server path traversal allows access to sibling directories sharing root_dir name prefix May 5, 2026
  • CVE-2025-61669 jupyter_server next parameter open redirect can redirect users to external domains May 5, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-114135 is "Jupyter Server: Gateway WebSocket handler bypasses kernel execute authorization", rated High. It affects Jupyter Server (Jupyter-server); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.8 describes technical severity. EPSS 0.48% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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