The Xen Project has published the following Xen Security Advisories: XSA-333, XSA-334, XSA-336, XSA-338, XSA-339, XSA-342, and XSA-344. 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/#333
https://www.qubes-os.org/security/xsa/#334
https://www.qubes-os.org/security/xsa/#336
https://www.qubes-os.org/security/xsa/#338
https://www.qubes-os.org/security/xsa/#339
https://www.qubes-os.org/security/xsa/#342
https://www.qubes-os.org/security/xsa/#344