{"id":"CVE-2020-11739","details":"An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service or possibly gain privileges because of missing memory barriers in read-write unlock paths. The read-write unlock paths don't contain a memory barrier. On Arm, this means a processor is allowed to re-order the memory access with the preceding ones. In other words, the unlock may be seen by another processor before all the memory accesses within the \"critical\" section. As a consequence, it may be possible to have a writer executing a critical section at the same time as readers or another writer. In other words, many of the assumptions (e.g., a variable cannot be modified after a check) in the critical sections are not safe anymore. The read-write locks are used in hypercalls (such as grant-table ones), so a malicious guest could exploit the race. For instance, there is a small window where Xen can leak memory if XENMAPSPACE_grant_table is used concurrently. A malicious guest may be able to leak memory, or cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded.","modified":"2026-03-15T22:32:24.845206Z","published":"2020-04-14T13:15:12.703Z","related":["SUSE-SU-2020:1124-1","SUSE-SU-2020:1138-1","SUSE-SU-2020:1139-1","SUSE-SU-2020:1630-1","SUSE-SU-2020:1634-1","SUSE-SU-2020:2234-1","openSUSE-SU-2020:0599-1","openSUSE-SU-2024:11520-1"],"references":[{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5M2XRNCHOGGTJQBZQJ7DCV6ZNAKN3LE2/"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NVTP4OYHCTRU3ONFJOFJQVNDFB25KLLG/"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YMAW7D2MP6RE4BFI5BZWOBBWGY3VSOFN/"},{"type":"ADVISORY","url":"http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00006.html"},{"type":"ADVISORY","url":"https://www.debian.org/security/2020/dsa-4723"},{"type":"ADVISORY","url":"https://security.gentoo.org/glsa/202005-08"},{"type":"FIX","url":"http://www.openwall.com/lists/oss-security/2020/04/14/2"},{"type":"FIX","url":"http://xenbits.xen.org/xsa/advisory-314.html"},{"type":"FIX","url":"https://xenbits.xen.org/xsa/advisory-314.html"}],"affected":[{"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-11739.json","unresolved_ranges":[{"events":[{"introduced":"0"},{"last_affected":"4.13.0"}]},{"events":[{"introduced":"0"},{"last_affected":"4.13.0-rc1"}]},{"events":[{"introduced":"0"},{"last_affected":"4.13.0-rc2"}]},{"events":[{"introduced":"0"},{"last_affected":"30"}]},{"events":[{"introduced":"0"},{"last_affected":"31"}]},{"events":[{"introduced":"0"},{"last_affected":"32"}]},{"events":[{"introduced":"0"},{"last_affected":"10.0"}]},{"events":[{"introduced":"0"},{"last_affected":"15.1"}]}]}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}