UBUNTU-CVE-2020-25596 (CVE-2020-25596)

Vulnerability from osv_ubuntu – Published: 2020-09-23 22:15 – Updated: 2026-04-22 07:39 – Source website
VLAI
Details

An issue was discovered in Xen through 4.14.x. x86 PV guest kernels can experience denial of service via SYSENTER. The SYSENTER instruction leaves various state sanitization activities to software. One of Xen's sanitization paths injects a #GP fault, and incorrectly delivers it twice to the guest. This causes the guest kernel to observe a kernel-privilege #GP fault (typically fatal) rather than a user-privilege #GP fault (usually converted into SIGSEGV/etc.). Malicious or buggy userspace can crash the guest kernel, resulting in a VM Denial of Service. All versions of Xen from 3.2 onwards are vulnerable. Only x86 systems are vulnerable. ARM platforms are not vulnerable. Only x86 systems that support the SYSENTER instruction in 64bit mode are vulnerable. This is believed to be Intel, Centaur, and Shanghai CPUs. AMD and Hygon CPUs are not believed to be vulnerable. Only x86 PV guests can exploit the vulnerability. x86 PVH / HVM guests cannot exploit the vulnerability.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 4.14.x. x86 PV guest kernels can experience denial of service via SYSENTER. The SYSENTER instruction leaves various state sanitization activities to software. One of Xen\u0027s sanitization paths injects a #GP fault, and incorrectly delivers it twice to the guest. This causes the guest kernel to observe a kernel-privilege #GP fault (typically fatal) rather than a user-privilege #GP fault (usually converted into SIGSEGV/etc.). Malicious or buggy userspace can crash the guest kernel, resulting in a VM Denial of Service. All versions of Xen from 3.2 onwards are vulnerable. Only x86 systems are vulnerable. ARM platforms are not vulnerable. Only x86 systems that support the SYSENTER instruction in 64bit mode are vulnerable. This is believed to be Intel, Centaur, and Shanghai CPUs. AMD and Hygon CPUs are not believed to be vulnerable. Only x86 PV guests can exploit the vulnerability. x86 PVH / HVM guests cannot exploit the vulnerability.",
  "id": "UBUNTU-CVE-2020-25596",
  "modified": "2026-04-22T07:39:31Z",
  "published": "2020-09-23T22:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2020-25596"
    },
    {
      "type": "REPORT",
      "url": "https://xenbits.xen.org/xsa/advisory-339.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-5617-1"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2020-25596"
    }
  ],
  "related": [
    "USN-5617-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2020-25596"
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.