CVE-2026-6550 PUBLISHED

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

Assigner: AMZN
Reserved: 17.04.2026 Published: 20.04.2026 Updated: 20.04.2026

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.

CVSS Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
CVSS Score: 4.7

Attack Vector	Local	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	None
Privileges Required	Low	Integrity Impact	High
User Interaction	None	Availability Impact	None

CVSS 3.1

CVSS 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
CVSS Score: 5.7

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Local	Confidentiality	None	Confidentiality	None
Attack Complexity	High	Integrity	High	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	Low
User Interaction	None

CVSS 4.0

Product Status

Vendor	AWS
Product	AWS Encryption SDK for Python
Versions	Default: unaffected affected from 2 to 2.5.1 (incl.) affected from 3 to 3.3.0 (incl.) affected from 4 to 4.0.4 (incl.)

Credits

1seal.org finder

References

Problem Types

CWE-757 Selection of Less-Secure algorithm during negotiation ('algorithm downgrade') CWE

Impacts

CAPEC-620 Drop Encryption Level