Ubuntu Security Notice 3576-1 - Vivian Zhang and Christoph Anton Mitterer discovered that libvirt incorrectly disabled password authentication when the VNC password was set to an empty string. A remote attacker could possibly use this issue to bypass authentication, contrary to expectations. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. Daniel P. Berrange discovered that libvirt incorrectly handled validating SSL/TLS certificates. A remote attacker could possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 17.10. Various other issues were also addressed.
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Debian Linux Security Advisory 4003-1 - Daniel P. Berrange reported that Libvirt, a virtualisation abstraction library, does not properly handle the default_tls_x509_verify (and related) parameters in qemu.conf when setting up TLS clients and servers in QEMU, resulting in TLS clients for character devices and disk devices having verification turned off and ignoring any errors while validating the server certificate.
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