ubuntu-cve-2020-11739
Vulnerability from osv_ubuntu
Published
2020-04-14 13:15
Modified
2026-04-22 07:39
Summary
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.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libxen-4.6",
            "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",
            "binary_version": "4.6.5-0ubuntu1.4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "xen",
        "purl": "pkg:deb/ubuntu/xen@4.6.5-0ubuntu1.4?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "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_name": "libxen-4.9",
            "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",
            "binary_version": "4.9.2-0ubuntu1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "xen",
        "purl": "pkg:deb/ubuntu/xen@4.9.2-0ubuntu1?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.9.0-0ubuntu3",
        "4.9.0-0ubuntu4",
        "4.9.2-0ubuntu1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "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",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "libxenforeignmemory1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "libxengnttab1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "libxenmisc4.11",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "libxenstore3.0",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "libxentoolcore1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "libxentoollog1",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-hypervisor-4.11-amd64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-hypervisor-4.11-arm64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-hypervisor-4.11-armhf",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-hypervisor-4.9-amd64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-hypervisor-4.9-arm64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-hypervisor-4.9-armhf",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-hypervisor-common",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-system-amd64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-system-arm64",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-system-armhf",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-utils-4.11",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xen-utils-common",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          },
          {
            "binary_name": "xenstore-utils",
            "binary_version": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "xen",
        "purl": "pkg:deb/ubuntu/xen@4.11.3+24-g14b62ab3e5-1ubuntu2.3?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.11.3+24-g14b62ab3e5-1ubuntu2.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "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"
      ]
    }
  ],
  "aliases": [],
  "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\u0027t 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.",
  "id": "UBUNTU-CVE-2020-11739",
  "modified": "2026-04-22T07:39:22Z",
  "published": "2020-04-14T13:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2020-11739"
    },
    {
      "type": "REPORT",
      "url": "https://xenbits.xen.org/xsa/advisory-314.html"
    },
    {
      "type": "REPORT",
      "url": "http://www.openwall.com/lists/oss-security/2020/04/14/2"
    },
    {
      "type": "REPORT",
      "url": "http://xenbits.xen.org/xsa/advisory-314.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-5617-1"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2020-11739"
    }
  ],
  "related": [
    "USN-5617-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2020-11739"
  ]
}



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