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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

3.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2026-22611: 0.24% estimated exploitation activity in the next 30 days; percentile 15.24 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

9 Jan 2026, 18:56 UTC

Last modified by the source

11 Jan 2026, 14:56 UTC

Source last checked

26 Oct 2026, 17:04 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-9cvc-h2w8-phrp

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# Patch Next advisory brief: CVE-2026-22611

Advisory: AWS SDK for .NET V4 adopted defense in depth enhancement for region parameter value
IDs: CVE-2026-22611, GHSA-9cvc-h2w8-phrp
Record: https://patchnext.com/advisories/cve-2026-22611 (revision 1, source checked 26 Oct 2026, 17:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: awssdk.core 4.0.3.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet awssdk.core: affected >= 4.0.0, < 4.0.3.3; fixed in 4.0.3.3

## Suggested inspection (read-only)
- NuGet awssdk.core: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on awssdk.core.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-9cvc-h2w8-phrp (GitHub-reviewed advisory GHSA-9cvc-h2w8-phrp lists affected ranges: NuGet awssdk.core >=4.0.0 <4.0.3.3)

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