ONNX symlink-following and path-traversal arbitrary file write
Summary
| CVE | CVE-2026-49114 |
|---|---|
| State | PUBLISHED |
| Assigner | cisa-cg |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-21 16:17:17 UTC |
| Updated | 2026-09-16 13:55:10 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 6.8 MEDIUM from 9119a7d8-5eab-497f-8521-727c672e3725
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.001070000 probability, percentile 0.012540000 (date 2026-08-26)
Problem Types: CWE-22 | CWE-59 | CWE-367 | CWE-367 CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition | CWE-22 CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | CWE-59 CWE-59 Improper Link Resolution Before File Access ('Link Following')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 9119a7d8-5eab-497f-8521-727c672e3725 | Secondary | 6.8 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | DECLARED | 6.8 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N |
| 3.1 | 9119a7d8-5eab-497f-8521-727c672e3725 | Secondary | 7.1 | HIGH | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H |
| 3.1 | CNA | DECLARED | 7.1 | HIGH | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H |
CVSS v4.0 Breakdown
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Linuxfoundation | Onnx | All | All | All | All |
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/onnx/onnx/security/advisories/GHSA-q56x-g2fj-4rj6 | 9119a7d8-5eab-497f-8521-727c672e3725 | github.com | Exploit, Vendor Advisory |
| raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-233-01.json | 9119a7d8-5eab-497f-8521-727c672e3725 | raw.githubusercontent.com | VDB Entry |
| www.cve.org/CVERecord | 9119a7d8-5eab-497f-8521-727c672e3725 | www.cve.org | Third Party Advisory, VDB Entry |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: tsigouris007 (en)
CNA: kpatsakis (en)