Segfault on strings tensors with mistmatched dimensions, due to Go code
Medium5.5CVE-2021-37692 · Published Aug 25, 2021 · updated Jul 8, 2026
### Impact Under certain conditions, Go code can trigger a segfault in string deallocation. For string tensors, `C.TF_TString_Dealloc` is called during garbage collection within a finalizer function. However, tensor structure isn't checked until encoding to avoid a performance penalty. The current method for dealloc assumes that encoding succeeded, but segfaults when a string tensor is garbage collected whose encoding failed (e.g., due to mismatched dimensions). To fix this, the call to set the finalizer function is deferred until `NewTensor` returns and, if encoding failed for a string tensor, deallocs are determined based on bytes written. ### Patches We have patched the issue in GitHub commit [8721ba96e5760c229217b594f6d2ba332beedf22](https://github.com/tensorflow/tensorflow/commit/8721ba96e5760c229217b594f6d2ba332beedf22) (merging [#50508](https://github.com/tensorflow/tensorflow/pull/50508)). The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, which is the other affected version. ### For more information Please consult [our security guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for more inform...
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| tensorflow PyPI | >= 2.5.0rc0, < 2.5.1 | 2.5.1 |
Details and references
### Impact Under certain conditions, Go code can trigger a segfault in string deallocation. For string tensors, `C.TF_TString_Dealloc` is called during garbage collection within a finalizer function. However, tensor structure isn't checked until encoding to avoid a performance penalty. The current method for dealloc assumes that encoding succeeded, but segfaults when a string tensor is garbage collected whose encoding failed (e.g., due to mismatched dimensions). To fix this, the call to set the finalizer function is deferred until `NewTensor` returns and, if encoding failed for a string tensor, deallocs are determined based on bytes written. ### Patches We have patched the issue in GitHub commit [8721ba96e5760c229217b594f6d2ba332beedf22](https://github.com/tensorflow/tensorflow/commit/8721ba96e5760c229217b594f6d2ba332beedf22) (merging [#50508](https://github.com/tensorflow/tensorflow/pull/50508)). The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, which is the other affected version. ### For more information Please consult [our security guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for more information regarding the security model and how to contact us with issues and questions. ### Attribution This vulnerability has been reported externally via a [fixing PR](https://github.com/tensorflow/tensorflow/pull/50508).
- CVSS 3.1
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Severity from
- GitHub (reviewed advisory)
- Weakness
- CWE-20
- Also known as
- BIT-tensorflow-2021-37692, CVE-2021-37692, PYSEC-2021-314, PYSEC-2021-605, PYSEC-2021-803
- github.com/tensorflow/tensorflow/security/advisories/GHSA-cmgw-8vpc-rc59
- nvd.nist.gov/vuln/detail/CVE-2021-37692
- github.com/tensorflow/tensorflow/pull/50508
- github.com/tensorflow/tensorflow/commit/8721ba96e5760c229217b594f6d2ba332beedf22
- github.com/pypa/advisory-database/tree/main/vulns/tensorflow-cpu/PYSEC-2021-605.yaml
- github.com/pypa/advisory-database/tree/main/vulns/tensorflow-gpu/PYSEC-2021-803.yaml
- github.com/pypa/advisory-database/tree/main/vulns/tensorflow/PYSEC-2021-314.yaml
- github.com/tensorflow/tensorflow
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