Medium severity · published Oct 26, 2026
CVE-2026-115922
ONNX: Denial of service via unchecked expansion of packed sub-byte tensors in ONNX Python APIs
New
6.2
CVSS
0.1%
EPSS
No
On KEV
Description
Open Neural Network Exchange (ONNX) is an open standard for machine learning interoperability. Prior to 1.22.0, _unpack_2bit() and _unpack_4bit() resize unpacked arrays according to attacker-controlled TensorProto.dims without verifying that raw_data or int32_data encodes the declared number of elements. Materializing an untrusted UINT2, INT2, UINT4, INT4, or FLOAT4E2M1 tensor through onnx.numpy_helper.to_array() or onnx.reference.ReferenceEvaluator can therefore expand a small packed payload into a disproportionately large allocation and exhaust memory. This issue is fixed in version 1.22.0.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 3% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ON
onnx · onnx
< 1.22.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-115922
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-115922
github.com
https://github.com/onnx/onnx/commit/05c1bc3bceceb8d3cf11e9e7fc7f19f971c44988
github.com
https://github.com/onnx/onnx/commit/8de2cf6aa47928e6515ac6d9e1a8b4758886a7df
github.com
https://github.com/onnx/onnx/commit/dce5876d6cc6cc30157af7d26a752ef44976da8e
github.com
https://github.com/onnx/onnx/pull/8033
github.com
https://github.com/onnx/onnx/pull/8038
github.com
https://github.com/onnx/onnx/pull/8066
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