{"id":"UBUNTU-CVE-2020-29571","details":"An issue was discovered in Xen through 4.14.x. A bounds check common to most operation time functions specific to FIFO event channels depends on the CPU observing consistent state. While the producer side uses appropriately ordered writes, the consumer side isn't protected against re-ordered reads, and may hence end up de-referencing a NULL pointer. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. Only Arm systems may be vulnerable. Whether a system is vulnerable depends on the specific CPU. x86 systems are not vulnerable.","modified":"2025-10-24T04:48:56Z","published":"2020-12-15T17:15:00Z","upstream":["CVE-2020-29571"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2020-29571"},{"type":"REPORT","url":"https://xenbits.xen.org/xsa/advisory-359.html"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2020-29571"}],"affected":[{"package":{"name":"xen","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/xen@4.6.5-0ubuntu1.4?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.5.1-0ubuntu1","4.5.1-0ubuntu2","4.6.0-1ubuntu1","4.6.0-1ubuntu2","4.6.0-1ubuntu4","4.6.0-1ubuntu4.1","4.6.0-1ubuntu4.2","4.6.0-1ubuntu4.3","4.6.5-0ubuntu1","4.6.5-0ubuntu1.1","4.6.5-0ubuntu1.2","4.6.5-0ubuntu1.4"],"ecosystem_specific":{"binaries":[{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"libxen-4.6"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"libxen-dev"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"libxenstore3.0"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-hypervisor-4.4-amd64"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-hypervisor-4.4-arm64"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-hypervisor-4.4-armhf"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-hypervisor-4.5-amd64"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-hypervisor-4.5-arm64"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-hypervisor-4.5-armhf"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-hypervisor-4.6-amd64"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-hypervisor-4.6-arm64"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-hypervisor-4.6-armhf"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-system-amd64"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-system-arm64"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-system-armhf"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-utils-4.6"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xen-utils-common"},{"binary_version":"4.6.5-0ubuntu1.4","binary_name":"xenstore-utils"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-29571.json"}},{"package":{"name":"xen","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/xen@4.9.2-0ubuntu1?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.9.0-0ubuntu3","4.9.0-0ubuntu4","4.9.2-0ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.9.2-0ubuntu1","binary_name":"libxen-4.9"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"libxen-dev"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"libxenstore3.0"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.6-amd64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.6-arm64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.6-armhf"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.7-amd64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.7-arm64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.7-armhf"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.8-amd64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.8-arm64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.8-armhf"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.9-amd64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.9-arm64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-hypervisor-4.9-armhf"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-system-amd64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-system-arm64"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-system-armhf"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-utils-4.9"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xen-utils-common"},{"binary_version":"4.9.2-0ubuntu1","binary_name":"xenstore-utils"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-29571.json"}},{"package":{"name":"xen","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/xen@4.11.3+24-g14b62ab3e5-1ubuntu2.3?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.9.2-0ubuntu2","4.9.2-0ubuntu6","4.9.2-0ubuntu7","4.11.3+24-g14b62ab3e5-1ubuntu1","4.11.3+24-g14b62ab3e5-1ubuntu2","4.11.3+24-g14b62ab3e5-1ubuntu2.2","4.11.3+24-g14b62ab3e5-1ubuntu2.3"],"ecosystem_specific":{"binaries":[{"binary_version":"4.11.3+24-g14b62ab3e5-1ubuntu2.3","binary_name":"libxen-dev"},{"binary_version":"4.11.3+24-g14b62ab3e5-1ubuntu2.3","binary_name":"libxencall1"},{"binary_version":"4.11.3+24-g14b62ab3e5-1ubuntu2.3","binary_name":"libxendevicemodel1"},{"binary_version":"4.11.3+24-g14b62ab3e5-1ubuntu2.3","binary_name":"libxenevtchn1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