CVE-2026-6550

medium

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.

References

https://aws.amazon.com/security/security-bulletins/2026-017-aws/

https://aws.amazon.com/security/security-bulletins/rss/2026-017-aws/

https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv

https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5

https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1

Details

Source: Mitre, NVD

Published: 2026-04-20

Updated: 2026-04-20

Risk Information

CVSS v2

Base Score: 3.8

Vector: CVSS2#AV:L/AC:H/Au:S/C:N/I:C/A:N

Severity: Low

CVSS v3

Base Score: 4.7

Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

Severity: Medium

CVSS v4

Base 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

Severity: Medium