Arbitrary file read via unchecked hardlinks
Published Apr 1, 2026 · Updated Apr 1, 2026
Path traversal in ONNX before 1.21.0 allows local users to read arbitrary files by supplying a crafted model with external data. The onnx.load validator in onnx/checker.cc rejects symbolic links but does not inspect inode link counts, so a hardlink to a sensitive file appears regular and passes validation. Exploitation requires a victim process to load the crafted model and the attacker to create a hardlink to a readable target on the same filesystem.
Summary
What happened
Path traversal in ONNX before 1.21.0 allows local users to read arbitrary files by supplying a crafted model with external data. The onnx.load validator in onnx/checker.cc rejects symbolic links but does not inspect inode link counts, so a hardlink to a sensitive file appears regular and passes validation. Exploitation requires a victim process to load the crafted model and the attacker to create a hardlink to a readable target on the same filesystem.
The record
- CVE
- CVE-2026-34446
- Published
- Apr 1, 2026
- Updated
- Apr 1, 2026
- Vendor
- ONNX
- Product
- ONNX
- Classifications
- CWE-61, CWE-22, T1204.002
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 1, 2026CVE publishedPublication date reported by the CVE source.
- Apr 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.21.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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