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.
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Affected Vendors & Products
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Advisories
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Fixes
Solution
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Workaround
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References
History
Fri, 21 Aug 2026 16:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | ONNX symlink-following and path-traversal arbitrary file write | |
| Weaknesses | CWE-22 CWE-367 CWE-59 |
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| Metrics |
cvssV3_1
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MITRE
Status: PUBLISHED
Assigner: cisa-cg
Published:
Updated: 2026-08-21T16:43:10.933Z
Reserved: 2026-05-27T16:19:04.848Z
Link: CVE-2026-49114
Vulnrichment
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NVD
Status : Received
Published: 2026-08-21T16:17:17.863
Modified: 2026-08-21T16:17:17.863
Link: CVE-2026-49114
Redhat
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OpenCVE Enrichment
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