# CVE-2026-8596: Cleartext storage of HMAC signing key in Amazon SageMaker Python SDK ModelBuilder/Serve path

> Authenticated attackers can extract HMAC keys from API responses to forge signatures and execute code in inference containers.

- **Severity:** High 8.5 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 May 2026
- **Updated:** 20 Oct 2026
- **Also known as:** GHSA-7hh5-prp2-mfh5, PYSEC-2026-3059

## What is CVE-2026-8596?

CVE-2026-8596 is a high-severity vulnerability in AWS Amazon SageMaker Python SDK, published on 14 May 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Cleartext storage of sensitive information in the ModelBuilder/Serve component in Amazon SageMaker Python SDK before v2.257.2 and v3 before v3.8.0 might allow a remote authenticated actor to extract the HMAC signing key from SageMaker API responses and forge valid integrity signatures for specially crafted model artifacts, achieving code execution in inference containers. This issue requires a remote authenticated actor with permissions to call SageMaker describe APIs and S3 write access to the model artifact path.

To remediate this issue, we recommend upgrading to Amazon SageMaker Python SDK v2.257.2 or v3.8.0 and rebuild any models previously created with ModelBuilder using the updated SDK.

Weakness: CWE-312 (Cleartext Storage of Sensitive Information)

## Which versions are affected by CVE-2026-8596?

5 open source packages ship an affected version, including sagemaker.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `sagemaker` | PyPI | From 2.199.0 | 2.257.2, 3.8.0 |
| `sagemaker` | PyPI | From 2.199.0 | 2.257.2 |
| `sagemaker` | PyPI | From 2.199.0 | 2.257.2 |
| `sagemaker` | PyPI | From 3.0.0 | 3.8.0 |
| `sagemaker` | PyPI | From 3.0.0 | 3.8.0 |

## How do I fix CVE-2026-8596?

Upgrade sagemaker to a fixed version for your release line: 2.257.2 or 3.8.0.

## Is CVE-2026-8596 being exploited?

There is no known exploitation of CVE-2026-8596 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-8596 and fix it if it is affected.

What it is: CVE-2026-8596 is a high-severity vulnerability in AWS Amazon SageMaker Python SDK, published on 14 May 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-8596 in the wild and no public exploit code.

Affected packages and fixed versions:
- sagemaker (PyPI): affected from 2.199.0; fixed in 2.257.2, 3.8.0
- sagemaker (PyPI): affected from 2.199.0; fixed in 2.257.2
- sagemaker (PyPI): affected from 2.199.0; fixed in 2.257.2
- sagemaker (PyPI): affected from 3.0.0; fixed in 3.8.0
- sagemaker (PyPI): affected from 3.0.0; fixed in 3.8.0

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-2026-8596/ (Markdown: https://insights.sbomify.com/CVE-2026-8596/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8596
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8596
- OSV: https://osv.dev/vulnerability/CVE-2026-8596

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-8596/
Summaries are generated and may contain mistakes; the official description above is the record.