# CVE-2021-37654: Heap OOB and CHECK fail in `ResourceGather` in TensorFlow

> An attacker can trigger a crash or read out-of-bounds heap memory in TensorFlow via the ResourceGather operation due to missing input validation.

- **Severity:** High 7.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/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-2021-37654, GHSA-2r8p-fg3c-wcj4, PYSEC-2021-276, PYSEC-2021-567, PYSEC-2021-765

## What is CVE-2021-37654?

CVE-2021-37654 is a high-severity memory corruption 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 trigger a crash via a `CHECK`-fail in debug builds of TensorFlow using `tf.raw_ops.ResourceGather` or a read from outside the bounds of heap allocated data in the same API in a release build. The [implementation](https://github.com/tensorflow/tensorflow/blob/f24faa153ad31a4b51578f8181d3aaab77a1ddeb/tensorflow/core/kernels/resource_variable_ops.cc#L660-L668) does not check that the `batch_dims` value that the user supplies is less than the rank of the input tensor. Since the implementation uses several for loops over the dimensions of `tensor`, this results in reading data from outside the bounds of heap allocated buffer backing the tensor. We have patched the issue in GitHub commit bc9c546ce7015c57c2f15c168b3d9201de679a1d. 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-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2021-37654?

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-2021-37654?

Upgrade tensorflow to a fixed version for your release line: 2.3.4, 2.4.3 or 2.5.1.

## Is CVE-2021-37654 being exploited?

There is no known exploitation of CVE-2021-37654 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-2021-37654 and fix it if it is affected.

What it is: CVE-2021-37654 is a high-severity memory corruption 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-2021-37654 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-2021-37654/ (Markdown: https://insights.sbomify.com/CVE-2021-37654/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-37654
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-37654
- OSV: https://osv.dev/vulnerability/CVE-2021-37654

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-37654/
Summaries are generated and may contain mistakes; the official description above is the record.
