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CVE-2026-73626

CVE-2026-73626 — JupyterLab before 4.6.2 Authentication Bypass via PyPIExtensionManager

JupyterLab versions >=4.6.0,<=4.6.1 and <=4.5.9 contain an allowlist/blocklist enforcement gap in PyPIExtensionManager.install(). A missing 'await' caused the is_install_allowed coroutine to never execute, so the extension allowlist/blocklist check was not enforced for direct callers of install(). The stock JupyterLab HTTP API and Extension Manager UI are not affected, as they perform a separate, correctly awaited check. The issue affects only deployments where a custom extension or downstream integration imports PyPIExtensionManager and calls install() directly with a package name influenced by untrusted input, an allowlist/blocklist is configured, the PyPI Extension Manager is enabled, and kernels and terminals are disabled or delegated to remote hosts. Fixed in JupyterLab 4.6.2 and 4.5.10.

Published Updated Sources: cvelistV5, VulnCheck

Triage

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

Exploitation

Unreported

no source claims exploitation

EPSS

0%

chance of exploitation in 30 days

Affects

jupyterlab

jupyterlab

CVSS base

0

NONE

CISA SSVC assessment

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

CISA

Exploitation

None

none · proof-of-concept · active

Automatable

No

can an attacker script all four kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (1)

jupyterlab

Products (1)

jupyterlab

Every base score collected

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

ScoreVersionSeverityExpl.ImpactSource
0CVSS 3.1NONE——cvelistV5

Weakness & attack patterns

  • CWE-284

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

  • T1027.009Obfuscated Files or Information: Embedded Payloads
  • T1546.004Event Triggered Execution: .bash_profile and .bashrc
  • T1546.016Event Triggered Execution: Installer Packages

Detection

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

  • Search application, proxy, and WAF logs for requests touching /blocklist.

References

2 on the record

Elsewhere on this site

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.