CVE-2026-6550

Key commitment policy bypass via shared key cache in AWS Encryption SDK for Python

Published Apr 20, 2026 CVSS 4.0 · 5.7 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-v638-38fc-rhfv AWS Encryption SDK for Python: Key commitment policy bypass via shared key cache
History
Type Values Removed Values Added
First Time appeared Amazon
Amazon aws Encryption Sdk For Python
Vendors & Products Amazon
Amazon aws Encryption Sdk For Python
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Key commitment policy bypass via shared key cache in AWS Encryption SDK for Python
Weaknesses CWE-757
References
Metrics cvssV3_1

{'score': 4.7, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N'}

cvssV4_0

{'score': 5.7, 'vector': 'CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
AMZN
Published
Updated
Apr 20, 2026, 7:44 PM
Reserved
Apr 17, 2026, 8:06 PM
Status
Awaiting Analysis
Published
Apr 20, 2026, 8:16 PM
Modified
Oct 26, 2026, 10:10 PM