ONNX: External Data Symlink Traversal

published 2026-04-01 7 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-17989 , GHSA-p433-9wv8-28xj , PYSEC-2026-104

cvss: 5.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits: 0; none known

Open Neural Network Exchange (ONNX) is an open standard for machine learning interoperability. Prior to version 1.21.0, there is a symlink traversal vulnerability in external data loading allows reading files outside the model directory. This issue has been patched in version 1.21.0.

Patch / fix

fixed in 3

pypi onnx 1.21.0
linuxfoundation onnx 1.21.0
onnx onnx 1.21.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-34447 updated 2026-04-02 cvss 5.5

onnx: ONNX: Information disclosure via symlink traversal in external data loading

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 7 mo ago (2026-04-01)

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/onnx/onnx/security/advisories/GHSA-p433-9wv8-28xj referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
GitHub	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
OSV	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
pypi	onnx	<1.21.0	1.21.0

Affected products

onnx onnx

Classification

Weakness

CWE-61 UNIX Symbolic Link (Symlink) Following
CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

github.com /onnx/onnx/security/advisories/GHSA-p433-9wv8-28xj
web, exploit, vendor-advisory, evidence
nvd.nist.gov /vuln/detail/CVE-2026-34447
advisory
github.com /onnx/onnx
package
github.com /pypa/advisory-database/tree/main/vulns/onnx/PYSEC-2026-104.yaml
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary