What is CVE-2026-22611?

CVE-2026-22611 is a low-severity improper input validation vulnerability in AWSSDK.Core (nuget), affecting versions >= 4.0.0, < 4.0.3.3. It is fixed in 4.0.3.3. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.

How severe is CVE-2026-22611?

CVE-2026-22611 has a CVSS score of 3.7 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of AWSSDK.Core are affected by CVE-2026-22611?

AWSSDK.Core (nuget) versions >= 4.0.0, < 4.0.3.3 is affected.

Is there a fix for CVE-2026-22611?

Yes. CVE-2026-22611 is fixed in 4.0.3.3. Upgrade to this version or later.

Is CVE-2026-22611 exploitable, and should I be worried?

Whether CVE-2026-22611 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2026-22611 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

How do I fix CVE-2026-22611?

Upgrade AWSSDK.Core to 4.0.3.3 or later.

CVE-2026-22611 in AWSSDK.Core

Q: How severe is CVE-2026-22611?

CVE-2026-22611 has a CVSS score of 3.7 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Q: Which versions of AWSSDK.Core are affected by CVE-2026-22611?

AWSSDK.Core (nuget) versions >= 4.0.0, < 4.0.3.3 is affected.

Q: Is there a fix for CVE-2026-22611?

Yes. CVE-2026-22611 is fixed in 4.0.3.3. Upgrade to this version or later.

Q: Is CVE-2026-22611 exploitable, and should I be worried?

Whether CVE-2026-22611 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2026-22611 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2026-22611?

Upgrade AWSSDK.Core to 4.0.3.3 or later.

Summary

AWS SDK for .NET V4 adopted defense in depth enhancement for region parameter value

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.

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

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)

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2026-22611 has a CVSS score of 3.7 (Low). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.0.3.3); upgrading removes the vulnerable code path.

Affected versions

AWSSDK.Core (>= 4.0.0, < 4.0.3.3)

Security releases

AWSSDK.Core → 4.0.3.3 (nuget)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

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.

Frequently Asked Questions

What is CVE-2026-22611? CVE-2026-22611 is a low-severity improper input validation vulnerability in AWSSDK.Core (nuget), affecting versions >= 4.0.0, < 4.0.3.3. It is fixed in 4.0.3.3. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
How severe is CVE-2026-22611? CVE-2026-22611 has a CVSS score of 3.7 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of AWSSDK.Core are affected by CVE-2026-22611? AWSSDK.Core (nuget) versions >= 4.0.0, < 4.0.3.3 is affected.
Is there a fix for CVE-2026-22611? Yes. CVE-2026-22611 is fixed in 4.0.3.3. Upgrade to this version or later.
Is CVE-2026-22611 exploitable, and should I be worried? Whether CVE-2026-22611 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2026-22611 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2026-22611? Upgrade AWSSDK.Core to 4.0.3.3 or later.