CVE-2026-22611
AWS SDK for .NET V4 adopted defense in depth enhancement for region parameter value
AWS SDK for .NET works with Amazon Web Services to help build scalable solutions with Amazon S3, Amazon DynamoDB, Amazon Glacier, and more. From versions 4.0.0 to before 4.0.3.3, Customer applications could be configured to improperly route AWS API calls to non-existent or non-AWS hosts. 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. This issue has been patched in version 4.0.3.3.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
AWS SDK for .NET V4 adopted defense in depth enhancement for region parameter value
AWS SDK for .NET works with Amazon Web Services to help build scalable solutions with Amazon S3, Amazon DynamoDB, Amazon Glacier, and more. From versions 4.0.0 to before 4.0.3.3, Customer applications could be configured to improperly route AWS API calls to non-existent or non-AWS hosts. 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. This issue has been patched in version 4.0.3.3.
- Record
CVE-2026-22611- CVSS 3.1
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-20
- Updated
- 2026-11-02
EUVDEUVD-2026-1697
AWS SDK for .NET works with Amazon Web Services to help build scalable solutions with Amazon S3, Amazon DynamoDB, Amazon Glacier, and more. From versions 4.0.0 to before 4.0.3.3, Customer applications could be configured to improperly route AWS API calls to non-existent or non-AWS hosts. 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. This issue has been patched in version 4.0.3.3.
- Record
EUVD-2026-1697- CVSS 3.1
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-9cvc-h2w8-phrp
AWS SDK for .NET V4 adopted defense in depth enhancement for region parameter value
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 [email protected].
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
- Record
GHSA-9cvc-h2w8-phrp- CVSS 3.1
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-20
- Updated
- 2026-11-02
NVD
AWS SDK for .NET works with Amazon Web Services to help build scalable solutions with Amazon S3, Amazon DynamoDB, Amazon Glacier, and more. From versions 4.0.0 to before 4.0.3.3, Customer applications could be configured to improperly route AWS API calls to non-existent or non-AWS hosts. 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. This issue has been patched in version 4.0.3.3.
- Record
CVE-2026-22611- CVSS 3.1
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-20
- Updated
- 2026-11-02
OSVGHSA-9cvc-h2w8-phrp
AWS SDK for .NET V4 adopted defense in depth enhancement for region parameter value
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 [email protected].
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
- Record
GHSA-9cvc-h2w8-phrp- CVSS 3.1
- 3.7 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-20
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
AWSSDK.CoreNuGet |
4.0.0 up to 4.0.3.3 | 4.0.3.3 |
AWSSDK.CoreNuGet |
4.0.0 up to 4.0.3.3, plus listed versions 4.0.0.14.0.0.104.0.0.114.0.0.124.0.0.13 Show 36 moreShow less4.0.0.144.0.0.154.0.0.164.0.0.174.0.0.184.0.0.194.0.0.24.0.0.204.0.0.214.0.0.224.0.0.234.0.0.244.0.0.254.0.0.264.0.0.274.0.0.284.0.0.294.0.0.34.0.0.304.0.0.314.0.0.324.0.0.334.0.0.44.0.0.54.0.0.64.0.0.74.0.0.84.0.0.94.0.14.0.1.14.0.1.24.0.1.34.0.24.0.34.0.3.14.0.3.2 |
4.0.3.3 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-22611 is a low vulnerability (CVSS 3.7) in Aws Aws-sdk-net, published January 9, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.24%, the 15th percentile. Fixed in AWSSDK.Core 4.0.3.3.