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I came across an interesting issue with the native 64-bit version of Citrix Workspace App 2603.11.
This is particularly interesting because 2603.11 is also one of the builds Citrix recommends updating to because of CVE-2026-78546 and CVE-2026-78547.
After the update, under certain conditions:
❌ Published applications and desktops may fail to start
❌ Domain pass-through authentication against StoreFront may fail
❌ Users may suddenly receive a credential prompt
The cause is related to a missing or incorrect reference to the 64-bit cck.dll.
Citrix has now documented a workaround:
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HKLM\SOFTWARE\Citrix\Receiver\Modules\cck.dll |
The following value must exist there:
Name: X64
Type: REG_SZ
Value: C:\Program Files\Citrix\ICA Client\Receiver\cck.dll
Via command line:
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reg add "HKLM\SOFTWARE\Citrix\Receiver\Modules\cck.dll" /v X64 /t REG_SZ /d "C:\Program Files\Citrix\ICA Client\Receiver\cck.dll" /f /reg:64 |
Citrix plans to include the fix in an upcoming 2603 release.
💡 The interesting part:
Security says: Upgrade to 2603.11 or later.
Operations says: Not without testing, especially with StoreFront + domain pass-through.
These are exactly the small details that are easy to overlook in a test environment and then cause trouble during a broad client rollout. 😉
Finding in the Wild: Anyone currently upgrading to CWA 2603.11 x64 should explicitly test app/desktop launch and domain pass-through.
