libvirt version before 4.2.0-rc1 is vulnerable to a resource exhaustion as a result of an incomplete fix for CVE-2018-5748 that affects QEMU monitor but now also triggered via QEMU guest agent.

util/virlog.c in libvirt does not properly determine the hostname on LXC container startup, which allows local guest OS users to bypass an intended container protection mechanism and execute arbitrary commands via a crafted NSS module.

qemu/qemu_monitor.c in libvirt allows attackers to cause a denial of service (memory consumption) via a large QEMU reply.

libvirt version 2.3.0 and later is vulnerable to a bad default configuration of "verify-peer=no" passed to QEMU by libvirt resulting in a failure to validate SSL/TLS certificates by default.

libvirt before 2.0.0 improperly disables password checking when the password on a VNC server is set to an empty string, which allows remote attackers to bypass authentication and establish a VNC session by connecting to the server.

The qemu implementation in libvirt before 1.3.0 and Xen allows local guest OS users to cause a denial of service (host disk consumption) by writing to stdout or stderr.

The networkReloadIptablesRules function in network/bridge_driver.c in libvirt before 0.9.9 does not properly handle firewall rules on bridge networks when libvirtd is restarted, which might allow remote attackers to bypass intended access restrictions via a (1) DNS or (2) DHCP query.

The virStorageVolCreateXML API in libvirt 1.2.14 through 1.2.19 allows remote authenticated users with a read-write connection to cause a denial of service (libvirtd crash) by triggering a failed unlink after creating a volume on a root_squash NFS pool.

Directory traversal vulnerability in the virStorageBackendFileSystemVolCreate function in storage/storage_backend_fs.c in libvirt, when fine-grained Access Control Lists (ACL) are in effect, allows local users with storage_vol:create ACL but not domain:write permission to write to arbitrary files via a .. (dot dot) in a volume name.

libvirt before 1.2.12 allow remote authenticated users to obtain the VNC password by using the VIR_DOMAIN_XML_SECURE flag with a crafted (1) snapshot to the virDomainSnapshotGetXMLDesc interface or (2) image to the virDomainSaveImageGetXMLDesc interface.