Log in Start free

Vulnerability · Published Apr 20, 2026 · Assigned by AMZN

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

Medium 4.7

In plain English

A medium-severity security flaw in AWS Encryption SDK for Python from AWS. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.7Medium
Exploit odds (30 days)<0.1%top 99.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
PyPIaws-encryption-sdk3.3.1GHSA-v638-38fc-rhfv
PyPIaws-encryption-sdk4.0.5GHSA-v638-38fc-rhfv
PyPIaws-encryption-sdk3.3.1, 4.0.5PYSEC-2026-2387

Affected products (as reported)

VendorProductVersions
AWS AWS Encryption SDK for Python 2 – through 2.5.13 – through 3.3.04 – through 4.0.4

Weakness: CWE-757 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

References