Update 2026-05-28-keystone.md

Update link for yaook security advisory

Signed-off-by: Stefan Hoffmann <31539613+mrhopeman@users.noreply.github.com>

Author: mrhopeman

blog/2026-05-28-keystone.md

@@ -74,7 +74,7 @@ functionality for services like Heat or image uploads.
 The SCS ecosystem software providers are providing fixed Keystone images:
 
 - [OSISM](https://osism.tech/docs/appendix/security/ossa-2026-015)
-- [yaook](https://yaook.cloud/security-advisories-cve-2026-33551)
+- [yaook](https://yaook.cloud/security-advisories-cve-2026-42998-43001-44394/)
 
 ## Outlook