The Xen Project has published Xen Security Advisories 317, 319, 327, and 328 (XSA-317, XSA-319, XSA-327, and XSA-328, respectively). These XSAs do not affect the security of Qubes OS, and no user action is necessary.

These XSAs have been added to the XSA Tracker:

https://www.qubes-os.org/security/xsa/#317
https://www.qubes-os.org/security/xsa/#319
https://www.qubes-os.org/security/xsa/#327
https://www.qubes-os.org/security/xsa/#328