diff --git a/docs/framework/release-notes/2026/08-11-august-cumulative-update.md b/docs/framework/release-notes/2026/08-11-august-cumulative-update.md index 1f7f25c3b7023..49b01ba36b79f 100644 --- a/docs/framework/release-notes/2026/08-11-august-cumulative-update.md +++ b/docs/framework/release-notes/2026/08-11-august-cumulative-update.md @@ -1,12 +1,13 @@ --- title: August 2026 cumulative update description: Learn about the improvements in the .NET Framework August 2026 cumulative update. -ms.date: 08/11/2026 +ms.date: 08/20/2026 ai-usage: ai-generated --- # .NET Framework August 2026 cumulative update _Released August 11, 2026_ +_Updated August 20, 2026, to include known issues._ ## Summary of what's new in this release @@ -45,7 +46,22 @@ There are no new quality and reliability improvements in this release. ## Known issues in this release -This release contains no known issues. +**Known issue:** After installing the August 2026 .NET Framework cumulative update, some WPF applications might fail with a `System.IO.FileFormatException` when printing or generating PDF/XPS content that uses certain fonts, including Calibri. + +**Workaround:** Applications can mitigate the issue by enabling the `Switch.MS.Internal.TtfDelta.DisableCmapAndSbitOverflowProtection` AppContext switch in the app config file, as shown below. + +```xml + + + + + +``` + +This switch disables security protections introduced in the August 2026 update and may increase exposure to the vulnerabilities addressed by that update. Microsoft recommends using this workaround only as a temporary measure and only when required to address this issue. + +**Status:** Investigating. ## Summary tables