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High, CVSS 8.8amended

nbconvert: Arbitrary file write through path traversal in cell output filenames when exporting to md, latex, rst and asciidoc

CVE-2026-114140GHSA-pjvx-prjx-h659

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (nbconvert 7.17.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • PyPI nbconvert

    Affected
    >= 5.4.0, <= 7.17.1
    Fixed in
    7.17.2

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.8 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H · score source
EPSS
  • CVE-2026-114140: 0.46% estimated exploitation activity in the next 30 days; percentile 39.50 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary nbconvert <= v7.17.1 has an arbitrary file write vulnerability due to a path traversal in ipynb cell output metadata, more specifically on the filename attribute. Vulnerable converters : --to markdown, --to latex, --to rst, --to asciidoc. In ExtractOutputPreprocessor, extractoutput.py:116-119 joins attacker-controlled path to outputfilesdir with no canonicalization check, enabling arbitrary file write. This is a sibling vulnerability of https://github.com/advisories/GHSA-4c99-qj7h-p3vg. Impact If a victim runs nbconvert on a malicious ipynb file, it can create some files with arbitrary data in arbitrary locations, i.e. override authorizedkeys. Note that running the cell with jupyter overrides the output, so it would "clean up" malicious cells. PoC In a ipynb file: Patches Fixed in - https://github.com/jupyter/nbconvert/commit/ce4bd99aec31d81d759fa8eeb8643179392ec66f - 7.17.2

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 5 · amended ·

    Amended from ghsa record GHSA-pjvx-prjx-h659

  2. Revision 4 · amended ·

    Amended from ghsa record GHSA-pjvx-prjx-h659

  3. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  4. Revision 2 · amended ·

    Amended from osv record GHSA-pjvx-prjx-h659

  5. Revision 1 · created ·

    Published from ghsa record GHSA-pjvx-prjx-h659

Agent brief

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# Patch Next advisory brief: CVE-2026-114140

Advisory: nbconvert: Arbitrary file write through path traversal in cell output filenames when exporting to md, latex, rst and asciidoc
IDs: CVE-2026-114140, GHSA-pjvx-prjx-h659
Record: https://patchnext.com/advisories/cve-2026-114140 (revision 5, source checked 26 Oct 2026, 13:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nbconvert 7.17.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI nbconvert: affected >= 5.4.0, <= 7.17.1; fixed in 7.17.2

## Suggested inspection (read-only)
- `python -m pip show nbconvert`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on nbconvert.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-pjvx-prjx-h659 (GitHub-reviewed advisory GHSA-pjvx-prjx-h659 lists affected ranges: PyPI nbconvert >=5.4.0 <=7.17.1)
- Verified: https://osv.dev/vulnerability/GHSA-pjvx-prjx-h659 (OSV record GHSA-pjvx-prjx-h659 lists affected ranges: PyPI nbconvert >=5.4.0 <7.17.2 (fixed))

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