EUVD-2026-63995
GHSA-486p-g8x4-77mg
Severity by source
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
Primary rating from Vendor (9119a7d8-5eab-497f-8521-727c672e3725).
CVSS VectorVendor: 9119a7d8-5eab-497f-8521-727c672e3725
Lifecycle Timeline
3Blast Radius
ecosystem impact- 24 pypi packages depend on onnx (14 direct, 10 indirect)
Ecosystem-wide dependent count for version 1.21.0.
DescriptionCVE.org
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.
AnalysisAI
Symlink-following arbitrary file write in ONNX's save_external_data function (onnx/external_data_helper.py) allows a local attacker with write access to a shared directory to redirect a victim's model serialization writes to any file the victim can modify — including ~/.ssh/authorized_keys, cron entries, and application configuration files. All ONNX releases up to and including 1.20.1 (pip/onnx) are affected; the vendor-released patch is 1.21.0. …
Unlock full vulnerability intelligence
- Risk assessment & exploitation conditions
- Attack chain visualization
- Remediation with exact patch versions
- Threat intelligence from 22 sources
- Personal watchlist & email alerts
Free forever · No credit card required
Threat intelligence, references, and detailed analysis are available after sign-in.
Same weakness CWE-22 – Path Traversal
View allSame technique Path Traversal
View allVendor StatusVendor
Share
External POC / Exploit Code
Leaving vuln.today