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.
Fix
Vendor advisories in the News 1
- CVE-2026-110310 - RSA PKCS#1 v1.5 padding oracle via legacy envelope key format downgrade in Amazon S3 Encryption Client for .NET AWS Security Bulletins · 2026-10-14
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 2
- StatusReceived → Awaiting AnalysisNVD modified 2026-10-16 15:20
- First seenCVSS 6.0NVD modified 2026-10-14 20:17
Affected (CPE criteria) 0
NVD has not attached CPE configurations yet.