This notification is related to the CloudFront signing utilities in the AWS SDK for PHP, 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.
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.
On 3/3/2026, an enhancement was made to the AWS SDK for PHP version 3.371.4. The enhancement ensures that special characters in input values are correctly handled. It is recommended to upgrade to the latest version.
No workarounds are needed, but customers should ensure that the application is following security best practices:
For any questions or comments about this advisory, it is recommended to contact AWS Security via the vulnerability reporting page or directly via email to aws-security@amazon.com. Please do not create a public GitHub issue.
The Amazon...
3.371.4Exploitability
AV:NAC:LAT:NPR:NUI:NVulnerable System
VC:NVI:LVA:NSubsequent System
SC:HSI:NSA:N7.7/CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:H/SI:N/SA:N