The Xen Project has published the following Xen Security Advisories: XSA-286, XSA-331, XSA-332, and XSA-345. These XSAs do not affect the security of Qubes OS, and no user action is necessary.

Special note: Although XSA-345 is included in QSB #060, we do not consider XSA-345 to affect the security of Qubes OS, since the default configuration is safe, and we have already implemented appropriate safeguards to prevent users from changing to a vulnerable configuration by accident. Please see the Impact section of QSB #060 for further details.

These XSAs have been added to the XSA Tracker:

https://www.qubes-os.org/security/xsa/#286
https://www.qubes-os.org/security/xsa/#331
https://www.qubes-os.org/security/xsa/#332
https://www.qubes-os.org/security/xsa/#345