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CVE-2026-40171VulnerabilityPublished Updated

In Jupyter Notebook versions 7.0.0 through 7.5.5, JupyterLab versions 4.5.6 and earlier, and the corresponding

Affects jupyter-notebookSource GCVE Database

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Authoritative record:CVE-2026-40171· High 8.4

Not known to be exploited · CVSS 8.4 High · fixed in 7.5.6 : patch jupyter-notebook soon.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 4.0 base score
8.4High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 7.5.6
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 6 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10jupyter-notebookpkg:deb/ubuntu/jupyter-notebook?arch=source&distro=stonkingOther threatsAffected
  • =6.4.13-5ubuntu0.1
Fixed in–
Ubuntu 25.10jupyter-notebookpkg:deb/ubuntu/jupyter-notebook?arch=source&distro=questingOther threatsAffected
  • =6.4.13-5
  • =6.4.13-5ubuntu0.1
Fixed in–
Ubuntu 20.04 LTSjupyter-notebookpkg:deb/ubuntu/jupyter-notebook?arch=source&distro=focalOther threatsAffected
  • 5.7.8-1 – 6.0.3-2ubuntu0.1
7 affected builds
Fixed in–
Ubuntu 18.04 LTSjupyter-notebookpkg:deb/ubuntu/jupyter-notebook?arch=source&distro=bionicOther threatsAffected
  • 4.2.3-4 – 5.2.2-1ubuntu0.1
5 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in Jupyter Notebook 7.5.6, JupyterLab 4.5.7, and the corresponding help-extension packages 7.5.6 and 4.5.7. Users should upgrade to these versions to remediate the vulnerability. As a workaround, disabling the affected help extensions or setting allowCommandLinker to false in the sanitizer configuration can mitigate the risk until patches are applied.

Description

A stored cross-site scripting (XSS) vulnerability exists in Jupyter Notebook versions 7.0.0 through 7.5.5, JupyterLab versions 4.5.6 and earlier, and related help-extension packages before 7.5.6 and 4.5.7. This flaw allows an attacker to craft malicious notebook content that, when interacted with by a user, can steal authentication tokens. Exploitation enables full session takeover via the REST API, including file access, code execution, and terminal creation. The issue is fixed in Notebook 7.5.6, JupyterLab 4.5.7, and corresponding help-extension updates. Workarounds include disabling affected help extensions or setting allowCommandLinker to false in sanitizer configuration.

References

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