# CVE-2021-37657: Reference binding to nullptr in `MatrixDiagV*` ops in TensorFlow > An attacker can cause undefined behavior and potential crashes in TensorFlow by providing an empty tensor to MatrixDiagV operations due to missing validation. - **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 12 Aug 2021 - **Updated:** 4 Aug 2024 - **Also known as:** BIT-tensorflow-2021-37657, GHSA-5xwc-mrhx-5g3m, PYSEC-2021-279, PYSEC-2021-570, PYSEC-2021-768 ## What is CVE-2021-37657? CVE-2021-37657 is a high-severity vulnerability in Google Tensorflow, published on 12 Aug 2021. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description TensorFlow is an end-to-end open source platform for machine learning. In affected versions an attacker can cause undefined behavior via binding a reference to null pointer in all operations of type `tf.raw_ops.MatrixDiagV*`. The [implementation](https://github.com/tensorflow/tensorflow/blob/84d053187cb80d975ef2b9684d4b61981bca0c41/tensorflow/core/kernels/linalg/matrix_diag_op.cc) has incomplete validation that the value of `k` is a valid tensor. We have check that this value is either a scalar or a vector, but there is no check for the number of elements. If this is an empty tensor, then code that accesses the first element of the tensor is wrong. We have patched the issue in GitHub commit f2a673bd34f0d64b8e40a551ac78989d16daad09. The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, TensorFlow 2.4.3, and TensorFlow 2.3.4, as these are also affected and still in supported range. Weakness: CWE-824 (Access of Uninitialized Pointer) ## Which versions are affected by CVE-2021-37657? 22 open source packages ship an affected version, including tensorflow, tensorflow-cpu and tensorflow-gpu. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `tensorflow` | Bitnami | From 2.3.0 | 2.3.4, 2.4.3, 2.5.1 | | `tensorflow` | PyPI | All versions | 2.3.4 | | `tensorflow` | PyPI | All versions | 2.3.4 | | `tensorflow` | PyPI | From 2.3.0 | 2.3.4, 2.4.3 | | `tensorflow` | PyPI | From 2.4.0 | 2.4.3 | | `tensorflow` | PyPI | From 2.4.0 | 2.4.3 | | `tensorflow` | PyPI | From 2.5.0 | 2.5.1 | | `tensorflow` | PyPI | From 2.5.0 | 2.5.1 | | `tensorflow-cpu` | PyPI | All versions | 2.3.4 | | `tensorflow-cpu` | PyPI | All versions | 2.3.4 | | `tensorflow-cpu` | PyPI | From 2.3.0 | 2.3.4, 2.4.3 | | `tensorflow-cpu` | PyPI | From 2.4.0 | 2.4.3 | | `tensorflow-cpu` | PyPI | From 2.4.0 | 2.4.3 | | `tensorflow-cpu` | PyPI | From 2.5.0 | 2.5.1 | | `tensorflow-cpu` | PyPI | From 2.5.0 | 2.5.1 | | `tensorflow-gpu` | PyPI | All versions | 2.3.4 | | `tensorflow-gpu` | PyPI | All versions | 2.3.4 | | `tensorflow-gpu` | PyPI | From 2.3.0 | 2.3.4, 2.4.3 | | `tensorflow-gpu` | PyPI | From 2.4.0 | 2.4.3 | | `tensorflow-gpu` | PyPI | From 2.4.0 | 2.4.3 | | `tensorflow-gpu` | PyPI | From 2.5.0 | 2.5.1 | | `tensorflow-gpu` | PyPI | From 2.5.0 | 2.5.1 | Products: Google Tensorflow. ## How do I fix CVE-2021-37657? Upgrade tensorflow to a fixed version for your release line: 2.3.4, 2.4.3 or 2.5.1. ## Is CVE-2021-37657 being exploited? There is no known exploitation of CVE-2021-37657 in the wild and no public exploit code. ## Other vulnerabilities in Google Tensorflow - [CVE-2023-25668](https://insights.sbomify.com/CVE-2023-25668/): TensorFlow vulnerable to heap out-of-buffer read in the QuantizeAndDequantize operation (critical 9.8) - [CVE-2018-7575](https://insights.sbomify.com/CVE-2018-7575/): Integer Overflow or Wraparound in Google TensorFlow (critical 9.8) - [CVE-2021-37678](https://insights.sbomify.com/CVE-2021-37678/): Arbitrary code execution due to YAML deserialization (critical 9.3) - [CVE-2021-35958](https://insights.sbomify.com/CVE-2021-35958/): Path traversal in n/a (critical 9.1) - [CVE-2020-15202](https://insights.sbomify.com/CVE-2020-15202/): Integer truncation in Shard API usage (critical 9.0) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-37657 and fix it if it is affected. What it is: CVE-2021-37657 is a high-severity vulnerability in Google Tensorflow, published on 12 Aug 2021. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-37657 in the wild and no public exploit code. Affected packages and fixed versions: - tensorflow (Bitnami): affected from 2.3.0; fixed in 2.3.4, 2.4.3, 2.5.1 - tensorflow (PyPI): affected all versions; fixed in 2.3.4 - tensorflow (PyPI): affected all versions; fixed in 2.3.4 - tensorflow (PyPI): affected from 2.3.0; fixed in 2.3.4, 2.4.3 - tensorflow (PyPI): affected from 2.4.0; fixed in 2.4.3 - tensorflow (PyPI): affected from 2.4.0; fixed in 2.4.3 - tensorflow (PyPI): affected from 2.5.0; fixed in 2.5.1 - tensorflow (PyPI): affected from 2.5.0; fixed in 2.5.1 - tensorflow-cpu (PyPI): affected all versions; fixed in 2.3.4 - tensorflow-cpu (PyPI): affected all versions; fixed in 2.3.4 - tensorflow-cpu (PyPI): affected from 2.3.0; fixed in 2.3.4, 2.4.3 - tensorflow-cpu (PyPI): affected from 2.4.0; fixed in 2.4.3 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-37657/ (Markdown: https://insights.sbomify.com/CVE-2021-37657/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-37657 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-37657 - OSV: https://osv.dev/vulnerability/CVE-2021-37657 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-37657/ Summaries are generated and may contain mistakes; the official description above is the record.