The Xen Project has published Xen Security Advisories 313, 314, 316, and 318 (XSA-313, XSA-314, XSA-316, and XSA-318, 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/#313
https://www.qubes-os.org/security/xsa/#314
https://www.qubes-os.org/security/xsa/#316
https://www.qubes-os.org/security/xsa/#318