CVE-2026-22611: AWSSDK.Core AWS SDK For .NET V4 Vulnerability

LOW
Advisory Identifier: GHSA-9cvc-h2w8-phrp
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CVSS 3.7
CWE-20
Published
Advisory Summary

CVE-2026-22611 is a LOW (CVSS 3.7) aws sdk for .net v4 vulnerability (CWE-20: Improper Input Validation) affecting AWSSDK.Core libraries in the NuGet ecosystem. The issue involves aws sdk for .net v4 adopted defense in depth enhancement for region parameter value. Remediation is available by upgrading affected packages to version 4.0.3.3.

CVE-2026-22611 at a Glance

CVE Identifier CVE-2026-22611
GHSA Identifier GHSA-9cvc-h2w8-phrp
Severity LOW
CVSS v3.1 Base Score 3.7
CWE Classification CWE-20: Improper Input Validation
Affected Product AWSSDK.Core
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 3.7

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-22611

To remediate this vulnerability, upgrade all affected AWSSDK.Core dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

AWSSDK.Core fixed: 4.0.3.3 
Upgrade AWSSDK.Core to 4.0.3.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for AWSSDK.Core

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-22611, inspect your project dependencies for AWSSDK.Core:

inspect dependencies for AWSSDK.Core

Analyze the terminal output to locate any version of AWSSDK.Core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.0.3.3), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In AWSSDK.Core, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary This notification is related to the use of specific values for the region input field when calling AWS services. An actor with access to the environment in which the SDK is used could set the region input field to an invalid value. A defense-in-depth enhancement has been implemented in the AWS SDK for .NET v4. This enhancement validates that a region used to construct an endpoint URL is a valid host label. The change was released on Nov 21, 2025. This advisory is informational to help customers understand their responsibilities regarding configuration security. ### Impact Customer applications could be configured to improperly route AWS API calls to non-existent or non-AWS hosts. While the SDK was functioning safely within the requirements of the shared responsibility model, additional safeguards have been added to support secure customer implementations. Impacted versions: All versions of the AWS SDK for .NET V4 prior to the 4.0.139.0 release (the AWS SDK for .NET V3 was not impacted) ### Patches On Nov 21, 2025, an enhancement [1] was made to the AWS SDK for .NET v4 release, which validates the formatting of a region, providing additional safeguards. ### Workarounds No workarounds are needed, but as always developers should ensure that their application is following security best practices: - Implement proper input validation in your application code - Update to the latest AWS SDK for .NET release on a regular basis - Follow AWS security best practices [2] for SDK configuration ### References Contact AWS Security via the vulnerability reporting page or email [aws-security@amazon.com](mailto:aws-security@amazon.com). ### Acknowledgement AWS SDK for .NET v4 thanks Guy Arazi for bringing these customer security considerations to our attention through the coordinated disclosure process. [1] https://github.com/aws/aws-sdk-net/pull/4150 [2] https://docs.aws.amazon.com/sdk-for-net/v4/developer-guide/security.html

CVE-2026-22611 Affected AWSSDK.Core Versions

1 component(s)
Fixed Versions:
4.0.3.3
Product / Package Ecosystem Affected Versions Fixed Version
AWSSDK.Core
nuget/AWSSDK.Core
NuGet
≥ 4.0.0
< 4.0.3.3
4.0.3.3

References

GitHub Advisory / Wiki ADVISORY
https://github.com/aws/aws-sdk-net/security/advisories/GHSA-9cvc-h2w8-phrp
NVD — CVE-2026-22611 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-22611
AWSSDK.Core Source Repository REPOSITORY
https://github.com/aws/aws-sdk-net

Frequently Asked Questions

What is CVE-2026-22611?
CVE-2026-22611 is a security vulnerability in AWSSDK.Core involving AWS SDK for .NET V4 adopted defense in depth enhancement for region parameter value under CWE-20: Improper Input Validation.
Which AWSSDK.Core versions are affected?
Affected versions include releases prior to 4.0.3.3 across affected packages: AWSSDK.Core.
What version fixes CVE-2026-22611?
Upgrading to 4.0.3.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is AWSSDK.Core affected?
Yes, AWSSDK.Core is affected in releases prior to 4.0.3.3. Upgrade your dependency to 4.0.3.3 or later.
What is the CVSS score of CVE-2026-22611?
CVE-2026-22611 has a CVSS v3.1 base score of 3.7 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-22611?
CVE-2026-22611 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check NuGet dependencies for CVE-2026-22611?
Run the dependency tree command: 'inspect dependencies for AWSSDK.Core'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9cvc-h2w8-phrp",
  "modified" : "2026-01-11T14:56:00Z",
  "published" : "2026-01-09T18:56:21Z",
  "aliases" : [ "CVE-2026-22611" ],
  "summary" : "AWS SDK for .NET V4 adopted defense in depth enhancement for region parameter value",
  "details" : "### Summary\nThis notification is related to the use of specific values for the region input field when calling AWS services. An actor with access to the environment in which the SDK is used could set the region input field to an invalid value.\n\nA defense-in-depth enhancement has been implemented in the AWS SDK for .NET v4. This enhancement validates that a region used to construct an endpoint URL is a valid host label. The change was released on Nov 21, 2025. This advisory is informational to help customers understand their responsibilities regarding configuration security.\n\n### Impact\nCustomer applications could be configured to improperly route AWS API calls to non-existent or non-AWS hosts. While the SDK was functioning safely within the requirements of the shared responsibility model, additional safeguards have been added to support secure customer implementations.\n\nImpacted versions: All versions of the AWS SDK for .NET V4 prior to the 4.0.139.0 release (the AWS SDK for .NET V3 was not impacted)\n\n### Patches\nOn Nov 21, 2025, an enhancement [1] was made to the AWS SDK for .NET v4 release, which validates the formatting of a region, providing additional safeguards. \n\n### Workarounds\nNo workarounds are needed, but as always developers should ensure that their application is following security best practices:\n- Implement proper input validation in your application code\n- Update to the latest AWS SDK for .NET release on a regular basis\n- Follow AWS security best practices [2] for SDK configuration\n\n### References\nContact AWS Security via the vulnerability reporting page or email [aws-security@amazon.com](mailto:aws-security@amazon.com).\n\n### Acknowledgement\nAWS SDK for .NET v4 thanks Guy Arazi for bringing these customer security considerations to our attention through the coordinated disclosure process.\n\n[1] https://github.com/aws/aws-sdk-net/pull/4150\n\n[2] https://docs.aws.amazon.com/sdk-for-net/v4/developer-guide/security.html",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "AWSSDK.Core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "4.0.3.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/aws/aws-sdk-net/security/advisories/GHSA-9cvc-h2w8-phrp"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-22611"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/aws/aws-sdk-net"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-09T18:56:21Z",
    "nvd_published_at" : "2026-01-10T06:15:51Z"
  }
}