CVE-2026-39377

Name	CVE-2026-39377
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1134889

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
nbconvert (PTS)	bullseye	5.6.1-3	fixed
	bullseye (security)	5.6.1-3+deb11u1	fixed
	bookworm	6.5.3-3	fixed
	trixie	7.16.6-1	vulnerable
	forky, sid	7.17.1-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Debian Bugs
nbconvert	source	bullseye	(not affected)
nbconvert	source	bookworm	(not affected)
nbconvert	source	(unstable)	7.17.1-1	1134889

Notes

[trixie] - nbconvert <no-dsa> (Minor issue)
[bookworm] - nbconvert <not-affected> (Vulnerable code introduced later)
[bullseye] - nbconvert <not-affected> (Vulnerable code introduced later)
https://github.com/jupyter/nbconvert/security/advisories/GHSA-4c99-qj7h-p3vg
Introduced after: https://github.com/jupyter/nbconvert/commit/27804f13185bcf1d55ab8cde7ae00dbd4a1e6a5b (v7.4.0)
Fixed by: https://github.com/jupyter/nbconvert/commit/ba5e5cdd737704388251fa55fa9e58f5752fa39d (v7.17.1)