CVE-2026-6550
Bulletin ID: 2026-017-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 2026/04/20 12:45 PM PDT Description: AWS Encryption SDK (ESDK) for Python is a client-side encryption library. We identified CVE-2026-6550, which describes an issue with a key commitment policy bypass via shared key cache. 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. Impacted versions: - From 2.0 to 2.5.1 - From 3.0 to 3.3.0 - From 4.0 to 4.0.4 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.
CSIRTS triage
- What
- A key commitment policy bypass via shared key cache may allow an authenticated local threat actor to bypass key commitment policy enforcement.
- Who is affected
- Authenticated users of AWS Encryption SDK for Python versions in the specified range.
- Urgency
- Remediation is important to prevent unauthorized decryption of ciphertext.
- Action
- Update to a version of AWS Encryption SDK for Python that addresses this issue.
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Exploitation outlook
- Low exploitation risk0.10% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 1% of all EPSS-scored CVEs.
Advisory coverage (1)
External references
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