CVE-2026-8596: Cleartext storage of HMAC signing key in Amazon SageMaker Python SDK ModelBuilder/Serve path
Telemetry drift only. No threshold crossed and no authority ruling changed.
CVE record, CISA KEV and EPSS as of 2026-10-18.
CVEs like this one computed, by meaning
What to do now held facts and links
- No fix version is held. The CNA's first reference is the place to look: github.com
- Record your decision, dated and frozen with today's evidence: patch by a date · mitigated by a compensating control · deferred · accepted the risk · not affected
- Check your version against the ranges this record publishes.
What it is stated by the CNA
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
- affected
- Amazon SageMaker Python SDK AWS
- versions
- No affected-version range in held sources.
- fixed in
- No fix version in held sources.
- fixed by package (from OSV advisories)
- sagemaker (PyPI): 2.257.2; 3.8.0 GHSA-7hh5-prp2-mfh5 PYSEC-2026-3059
- severity
- 7.2 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- assigned by
- AMZN
- published
- 2026-05-14
check us github.com github.com aws.amazon.com github.com
Exploit code held, dated
- exploit code
- None held in the PoC-in-GitHub feed. A public repository changes this brief.
What moved held, dated
| date | EPSS | event |
|---|---|---|
| 15 May 2026 | 0.00165 | |
| 20 May 2026 | 0.001 | |
| 22 May 2026 | 0.00055 | |
| 15 Jun 2026 | 0.00439 | scoring model v2026.06.15 |
| 28 Aug 2026 | 0.00561 | |
| 28 Sep 2026 | 0.00802 |
6 observations held. A step marked with a scoring model moved because the measurement was replaced, not because the vulnerability changed.
Outside the record researched, cited
This section reads the record's references and adds cited findings from outside it. It needs an account. Everything above is held facts and is complete without it.
What would change this brief held, dated
- CISA KEV
- Not listed in the catalogue we hold. A listing changes this brief.
- exploit probability
- 0.01 on 2026-09-28 (FIRST's EPSS, a probability and not evidence of exploitation). Next band line: 10% (0.10). Crossing a line changes this brief.
- fix
- No fix version is held. One published by the CNA or OSV changes this brief.
How to check this
Every value above is held with two dates: when it was true upstream (as_of) and when we recorded it (tx_from). Re-derive the exploit probability as it stood on any date:
SELECT value, source, source_version, as_of, tx_from
FROM volatile_valid_as_of('CVE-2026-8596', '2026-10-29T23:59:59.999999Z', now());