# CVE-2026-6550: Key commitment policy bypass via shared key cache in AWS Encryption SDK for Python

> CVE-2026-6550: Key commitment policy bypass via shared key cache in AWS Encryption SDK for Python. CVSS 4.7 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-6550
Last updated: 2026-06-17T11:00:57Z

- Published: 2026-04-20 19:20 UTC · Updated: 2026-06-17 11:00 UTC · Assigner: AMZN
- CVSS: 4.7 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
- EPSS: 0.10%, 1th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-757

## Description

Cryptographic algorithm downgrade in the caching layer of Amazon AWS Encryption SDK for Python before version 3.3.1 and before version  4.0.5 might allow an authenticated local threat actor to bypass key commitment policy enforcement via a shared key cache, resulting in ciphertext that can be decrypted to multiple different plaintexts. To remediate this issue, users should upgrade to version 3.3.1, 4.0.5 or above.

## Affected vendors and products

- AWS: AWS Encryption SDK for Python

## Tracked companies

- [Amazon Web Services](https://rewindex.com/company/aws.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-6550)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-6550)
- [https://aws.amazon.com/security/security-bulletins/2026-017-aws/](https://aws.amazon.com/security/security-bulletins/2026-017-aws/)
- [https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1](https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1)
- [https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5](https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5)
- [https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv](https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-6550 · Markdown: https://rewindex.com/cve/CVE-2026-6550.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-6550 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:13:25.982Z