CVE-2026-110310: RSA PKCS#1 v1.5 padding oracle via legacy envelope key format downgrade in Amazon S3 Encryption Client for .NET
Amazon · Amazon.Extensions.S3.Encryption
Vendor fix available · Affected: Amazon.Extensions.S3.Encryption · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 43% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- Amazon · Amazon.Extensions.S3.Encryptionfrom 2.1.0 up to and including 2.*; from 3.0.0 up to and including 3.2.1; from 4.0.0 up to and including 4.0.2
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- Amazon
- Published
- October 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-110310 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.