5.7

CVE-2026-6550: aws aws encryption sdk for python Algorithm Downgrade

CVSS: 5.7v4.0MediumAwaiting analysis
AliasesGHSA-v638-38fc-rhfvPYSEC-2026-2387
Published 20-04-2026Last modified 20-04-2026
Open JSON

Vulnerability summary

CVE-2026-6550 is a medium (CVSS 5.7) Algorithm Downgrade vulnerability in aws aws encryption sdk for python. EPSS estimates a 0.10% chance of exploitation in the next 30 days, higher than 0.7% of scored vulnerabilities.

Overall risk
23/100
0100
Low · default modelHow is this calculated?
CVSS score
5.7/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.10%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 20-04-2026
    PublishedVulnerability first disclosed.
  2. 20-04-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

6 scores · 3 sources · 2 versions

EPSS trend

Probability

0.10%

Chance of exploitation in the next 30 days

Percentile

1%

Versus all other CVEs

30-day change

0.00 pp

From 0.10% on 18-09-2026

18-09-202618-10-2026
EPSS score
0.10%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Aws1 product
PyPI1 product
  • aws-encryption-sdk≥ 2.0.0, < 3.3.1 | ≥ 4.0.0, < 4.0.5

2 vendors · 2 products

References

10 links