Amazon AWS Encryption SDK for Python up to 2.5.1/3.3.0/4.0.4 Caching Layer downgrade

CVSS Meta Temp Score
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CTI Interest Score
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3.6$0-$5k8.82

Summaryinfo

A vulnerability was found in Amazon AWS Encryption SDK for Python up to 2.5.1/3.3.0/4.0.4. It has been rated as problematic. This issue affects some unknown processing of the component Caching Layer. This manipulation causes downgrade. This vulnerability is handled as CVE-2026-6550. It is possible to launch the attack on the local host. There is not any exploit available.

Detailsinfo

A vulnerability was found in Amazon AWS Encryption SDK for Python up to 2.5.1/3.3.0/4.0.4. It has been declared as problematic. Affected by this vulnerability is an unknown function of the component Caching Layer. The manipulation with an unknown input leads to a downgrade vulnerability. The CWE definition for the vulnerability is CWE-757. A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties. As an impact it is known to affect integrity. The summary by CVE is:

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.

The weakness was released by 1seal.org. It is possible to read the advisory at aws.amazon.com. This vulnerability is known as CVE-2026-6550 since 04/17/2026. The exploitation appears to be difficult. Attacking locally is a requirement. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1562.010 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-23943). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 3.6
VulDB Meta Temp Score: 3.6

VulDB Base Score: 2.5
VulDB Temp Score: 2.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.7
CNA Vector (AMZN): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Downgrade
CWE: CWE-757
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

04/17/2026 CVE reserved
04/20/2026 +3 days Advisory disclosed
04/20/2026 +0 days VulDB entry created
04/20/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: aws.amazon.com
Researcher: 1seal.org
Status: Confirmed

CVE: CVE-2026-6550 (🔒)
GCVE (CVE): GCVE-0-2026-6550
GCVE (VulDB): GCVE-100-358351
EUVD: 🔒

Entryinfo

Created: 04/20/2026 21:48
Updated: 04/20/2026 23:33
Changes: 04/20/2026 21:48 (75), 04/20/2026 23:33 (1)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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