AWS SDK for .NET: Improper escaping of special characters in CloudFront policy document construction
Key facts
- Attack vector
- —
- Privileges required
- —
- User interaction
- —
- Attack complexity
- —
- Impact type
- —
- Confidentiality · integrity · availability
- —
- Fix status
- Fixed
No CVSS vector from any source. Fix status from GitHub.
Summary
### Summary This notification is related to the CloudFront signing utilities in the AWS SDK for .NET, which are used to generate Amazon CloudFront signed URLs and signed cookies. A defense-in-depth enhancement has been implemented to improve handling of special characters, such as double quotes and backslashes, in input values. ### Impact The CloudFront signing utilities build policy documents that define access restrictions for signed URLs and cookies. If an application passes unsanitized input containing special characters to these utilities, the resulting policy document may not reflect the application's intended access restrictions. While the SDK was functioning safely within the requirements of the shared responsibility model, additional safeguards have been added to support secure customer implementations. Applications that already follow AWS security best practices for input validation are not impacted. ### Impacted versions: - AWS SDK for .NET V3 (`AWSSDK.CloudFront`): < 3.7.510.7 - AWS SDK for .NET V4 (`AWSSDK.Extensions.CloudFront.Signers`): 4.0.0.0 - 4.0.0.25 ### Patches On February 25th, 2026, an enhancement was made to the AWS SDK for .NET CloudFront signing utilities. The enhancement ensures that special characters in input values are correctly handled. We recommend upgrading to the latest version. ### Workarounds No workarounds are needed, but customers should ensure that your application is following security best practices: - Implement proper input validation in your application code before passing values to CloudFront signing utilities - Update to the latest AWS SDK release on a regular basis - Follow AWS security best practices for SDK configuration ### References If there are any questions or comments about this advisory, contact AWS Security via our [vulnerability reporting page](https://aws.amazon.com/security/vulnerability-reporting) or directly via email to [[email protected]](mailto:[email protected]). Please do not create a public GitHub issue. ### Acknowledgement AWS SDK for .NET thanks the Amazon Inspector Security Research team for identifying this issue and working through the coordinated process together.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | AWSSDK.CloudFront (NuGet) | before 3.7.510.7 | 3.7.510.7 | Patch available | GHSA-mvm6-f9r3-fgfx |
| — | AWSSDK.Extensions.CloudFront.Signers (NuGet) | 4.0.0.0 to before 4.0.0.26 | 4.0.0.26 | Patch available | GHSA-mvm6-f9r3-fgfx |
- AWSSDK.CloudFront (NuGet) Vendor— Affected before 3.7.510.7 Fixed in 3.7.510.7 Patch available GHSA-mvm6-f9r3-fgfx
- AWSSDK.Extensions.CloudFront.Signers (NuGet) Vendor— Affected 4.0.0.0 to before 4.0.0.26 Fixed in 4.0.0.26 Patch available GHSA-mvm6-f9r3-fgfx
Remediation
- Fix · GHSA-mvm6-f9r3-fgfx AWSSDK.CloudFront (NuGet) Fixed in 3.7.510.7 Advisory →
- Fix · GHSA-mvm6-f9r3-fgfx AWSSDK.Extensions.CloudFront.Signers (NuGet) Fixed in 4.0.0.26 Advisory →
Timeline
- 2026-10-03 Threatist record created from GHSA-mvm6-f9r3-fgfx
References
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences