CVE-2026-114140 jupyter CVE debrief

Who should care

Defenders responsible for managing and securing Jupyter notebooks and nbconvert installations should be aware of this vulnerability and take necessary actions to prevent exploitation.

Why it matters

The nbconvert vulnerability allows for arbitrary file writes due to a path traversal issue, potentially leading to security breaches if exploited.

• Verify and upgrade nbconvert versions to prevent exploitation.
• Be cautious when running nbconvert on untrusted ipynb files to prevent arbitrary file writes.
• Monitor systems for suspicious file creations to detect potential exploitation.
• Implement additional security measures to prevent exploitation.

Technical summary

The nbconvert package has a vulnerability that allows for arbitrary file writes due to a path traversal issue in cell output filenames when exporting to certain formats. This vulnerability affects nbconvert versions up to 7.17.1 and can be exploited if a victim runs nbconvert on a malicious ipynb file, potentially leading to the creation of files with arbitrary data in arbitrary locations. The vulnerability is caused by a path traversal issue in the ExtractOutputPreprocessor of nbconvert, specifically in the extractoutput.py file. This allows an attacker to write arbitrary files with arbitrary data by manipulating the filename attribute in the cell output metadata of a malicious ipynb file. Defenders should be

Defensive priority

Defenders should prioritize verifying their nbconvert versions and upgrading to 7.17.2 or later if necessary. They should also be cautious when running nbconvert on untrusted ipynb files and monitor their systems for suspicious file creations.

Recommended defensive actions

• Verify nbconvert version and upgrade to 7.17.2 or later if necessary.
• Be cautious when running nbconvert on untrusted ipynb files.
• Monitor systems for suspicious file creations.
• Implement additional security measures to prevent exploitation.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The vulnerability is caused by a path traversal issue in the ExtractOutputPreprocessor of nbconvert, specifically in the extractoutput.py file. This allows an attacker to write arbitrary files with arbitrary data by manipulating the filename attribute in the cell output metadata of a malicious ipynb file.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.