CVE-2026-6550 (CVSS 4.7)

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.

Is your site exposed to CVE-2026-6550?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.7

MEDIUM

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

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-757 CWE-757

References

Other References

https://aws.amazon.com/security/security-bulletins/2026-017-aws/ https://github.com/aws/aws-encryption-sdk-python/releases/tag/v3.3.1 https://github.com/aws/aws-encryption-sdk-python/releases/tag/v4.0.5 https://github.com/aws/aws-encryption-sdk-python/security/advisories/GHSA-v638-38fc-rhfv

Frequently Asked Questions

What is CVE-2026-6550? +

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. It has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2026-6550? +

CVE-2026-6550 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-6550? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2024-8773

SIMPLE.ERP client is vulnerable to MS SQL protocol downgrade request from a server side, what could lead to an unencrypted …

CVE-2025-10693

When SmartStart Inclusion fails during the onboarding of a Z-Wave PIR sensor, the sensor will join the network as a …

CVE-2024-4995 9.8

Wapro ERP Desktop is vulnerable to MS SQL protocol downgrade request from a server side, what could lead to an …

CVE-2025-24154 9.1

An out-of-bounds write was addressed with improved input validation. This issue is fixed in iOS 18.3 and iPadOS 18.3, macOS …

CVE-2024-38883 9.1

An issue in Horizon Business Services Inc. Caterease 16.0.1.1663 through 24.0.1.2405 and possibly later versions, allows a remote attacker to …

CVE-2026-32650 7.5

Anviz CrossChex Standard is vulnerable when an attacker manipulates the TDS7 PreLogin to disable encryption, causing database credentials to be …

CVE-2026-6550