CVE-2021-32798Public exploitNetwork attack vector

Code execution via Caja sanitizer bypass

Published Aug 9, 2021 · Updated Aug 3, 2024

Cross-site scripting in Project Jupyter's Jupyter Notebook before 5.7.11 and 6.0.0 through 6.4.0 allows attackers to run code via malicious notebook. The front-end HTML sanitization path uses deprecated Caja, which misparses a select-wrapped iframe and leaves an image event handler executable. A victim must open the untrusted ipynb file; the resulting script can invoke Jupyter APIs and execute arbitrary code on the victim host.

CVSS severity7.8
High
EPSS probability2.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Project Jupyter's Jupyter Notebook before 5.7.11 and 6.0.0 through 6.4.0 allows attackers to run code via malicious notebook. The front-end HTML sanitization path uses deprecated Caja, which misparses a select-wrapped iframe and leaves an image event handler executable. A victim must open the untrusted ipynb file; the resulting script can invoke Jupyter APIs and execute arbitrary code on the victim host.

The record

CVE
CVE-2021-32798
Published
Aug 9, 2021
Updated
Aug 3, 2024
Vendor
Project Jupyter
Product
Jupyter Notebook
Classifications
CWE-80, CWE-79, CWE-75, T1203, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 5.7.11
  2. Affected versionversion=>= 6.0.0, < 6.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Project Jupyter · Jupyter Notebookversion=< 5.7.11; version=>= 6.0.0, < 6.4.1

Published CVSS scores

7.8GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-75Failure to Sanitize Special Elements into a Different Plane (Special Element Injection)
T1203Exploitation for Client Execution
T1204.002User Execution: Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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