Bug 2459951 (CVE-2026-39377)

Summary: CVE-2026-39377 nbconvert: nbconvert: Arbitrary file write via crafted Jupyter notebook cell attachment filenames
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: anthomas, ehelms, ggainey, jkoehler, juwatts, lphiri, mhulan, nmoumoul, osousa, pcreech, rchan, rjohnson, smallamp, tmalecek
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in nbconvert, a tool used to convert Jupyter notebooks. When processing notebooks containing specially crafted cell attachment filenames, a remote attacker can exploit a path traversal vulnerability. This allows the attacker to write arbitrary files to locations outside the intended output directory, gaining complete control over both the destination path and file extension.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-04-21 02:01:56 UTC
The nbconvert tool, jupyter nbconvert, converts Jupyter notebooks to various other formats via Jinja templates. Versions 6.5 through 7.17.0 allow arbitrary file writes to locations outside the intended output directory when processing notebooks containing crafted cell attachment filenames. The `ExtractAttachmentsPreprocessor` passes attachment filenames directly to the filesystem without sanitization, enabling path traversal attacks. This vulnerability provides complete control over both the destination path and file extension. Version 7.17.1 contains a patch.