CVE-2026-110310

A remote user who can read encrypted objects in the S3 bucket can force a padding downgrade by altering the padding scheme recorded in an object's metadata to legacy PKCS#1 v1.5. Since this padding scheme is susceptible to the well-known Bleichenbacher attack, the user can use a PKCS#1 v1.5 padding oracle to recover the RSA-wrapped envelope key and decrypt the object. To remediate this issue, we recommend that users upgrade to version 3.2.2 or 4.0.3. The 1.x and 2.x lines will not be patched, users of those lines need to migrate to 3.2.2 or 4.0.3.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.6 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://aws.amazon.com/security/security-bulletins/2026-135-aws/
https://github.com/aws/amazon-s3-encryption-client-dotnet/security/advisories/GHSA-322w-f6rw-r4fj
https://www.nuget.org/packages/Amazon.Extensions.S3.Encryption/3.2.2
https://www.nuget.org/packages/Amazon.Extensions.S3.Encryption/4.0.3

Configurations

No configuration.

History

14 Oct 2026, 20:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-14 20:17

Updated : 2026-10-16 15:20

NVD link : CVE-2026-110310

Mitre link : CVE-2026-110310

CVE.ORG link : CVE-2026-110310

JSON object : View

Products Affected

No product.

CWE

CWE-204

Observable Response Discrepancy

CWE-757

Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')

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