CVE-2026-49114

Name	CVE-2026-49114
Description	In ONNX before 1.21.0, the 'save_external_data' function builds the external-data file path from the model's external_data location field and opens it for writing without 'O_NOFOLLOW/O_EXCL', after a non-atomic 'os.path.isfile()' check. A local attacker with write access to the directory where a victim serializes external data can deterministically pre-plant a symlink that is being followed, causing the victim's write to append to any file the victim can write, e.g. ~/.ssh/authorized_keys, cron files, or application configs. Fixed in 1.21.0.
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	1145196

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
onnx (PTS)	bookworm	1.12.0-2	vulnerable
	trixie	1.17.0-3	vulnerable
	forky, sid	1.20.0-6	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
onnx	source	(unstable)	(unfixed)			1145196

Notes

[trixie] - onnx <no-dsa> (Minor issue)
[bookworm] - onnx <postponed> (Minor issue)
https://github.com/onnx/onnx/security/advisories/GHSA-q56x-g2fj-4rj6