Detections
Analytics

NuGet Package 'Amazon.Extensions.S3.Encryption' 2.1.x <= 2.3.0 / 3.x < 3.2.2 / 4.0.x < 4.0.3 RSA Padding Oracle

medium Nessus Plugin ID 373616

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Synopsis

The remote host has a NuGet package installed that is affected by an information disclosure vulnerability.

Description

The version of the NuGet Package 'Amazon.Extensions.S3.Encryption' (Amazon S3 Encryption Client for .NET) installed on the remote host is 2.x greater than or equal to 2.1.0, or 3.x prior to 3.2.2, or 4.0.x prior to 4.0.3. It is, therefore, affected by a padding oracle vulnerability. 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.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update the 'Amazon.Extensions.S3.Encryption' package to version 3.2.2 (3.x) or 4.0.3 (4.x) or later. Note that the 1.x and 2.x lines will not receive patches; users of those versions need to migrate to version 3.2.2 or 4.0.3.

See Also

https://aws.amazon.com/security/security-bulletins/2026-135-aws/

https://www.nuget.org/packages/Amazon.Extensions.S3.Encryption/

http://www.nessus.org/u?a6838ca3

Plugin Details

Severity: Medium

ID: 373616

File Name: nuget_pkg_amazon_extensions_s3_encryption_3_2_2_4_0_3.nasl

Version: 1.2

Type: Local

Agent: windows, macosx, unix

Family: Misc.

Published: 10/29/2026

Updated: 10/30/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.67

CVSS v2

Risk Factor: Medium

Base Score: 4.9

Vector: CVSS2#AV:N/AC:H/Au:S/C:C/I:N/A:N

CVSS Score Source: CVE-2026-110310

CVSS v3

Risk Factor: Medium

Base Score: 5.3

Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS v4

Risk Factor: Medium

Base Score: 6

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Vulnerability Information

CPE: cpe:/a:microsoft:nuget

Required KB Items: NuGet/Packages/Enumerated

Patch Publication Date: 7/1/2026

Vulnerability Publication Date: 10/14/2026

Reference Information

CVE: CVE-2026-110310

CWE: 204, 757

IAVA: 2026-A-1209