CVE-2026-49114
Published:August 21, 2026
Updated:September 24, 2026
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.
Affected Packages
onnx (CONDA):
Affected version(s) >=0.2.1 <1.21.0Fix Suggestion:
Update to version 1.21.0onnx (CONDA):
Affected version(s) >=0.2.1 <1.21.0Fix Suggestion:
Update to version 1.21.0https://github.com/onnx/onnx.git (GITHUB):
Affected version(s) >=v0.1 <v1.21.0Fix Suggestion:
Update to version v1.21.0onnx (PYTHON):
Affected version(s) >=0.1 <1.21.0Fix Suggestion:
Update to version 1.21.0onnx (PYTHON):
Affected version(s) >=0.1 <1.21.0Fix Suggestion:
Update to version 1.21.0Related Resources (6)
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Contact UsCVSS v4
Base Score:
6.8
Attack Vector
LOCAL
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
ACTIVE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.1
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
HIGH
Weakness Type (CWE)
EPSS
Base Score:
0.16