CVE-2026-110310
Received
Received - Intake
Padding Oracle Attack in AWS S3 Encryption
Vulnerability report for CVE-2026-110310, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-14
Last updated on: 2026-10-14
Assigner: AMZN
Description
Description
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 Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Amazon | Amazon.Extensions.S3.Encryption | 2.1.0 |
| Amazon | Amazon.Extensions.S3.Encryption | 3.0.0 |
| Amazon | Amazon.Extensions.S3.Encryption | 4.0.0 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| 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. |
| CWE-204 | The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere. |
