What is the CVSS score of CVE-2019-18425?

CVE-2019-18425 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 2.5%.

Is there a patch available for CVE-2019-18425?

Yes, a patch is available for CVE-2019-18425. Update the affected software to the latest version immediately.

Xen CVE-2019-18425

CRITICAL

Improper Privilege Management (CWE-269)

2019-10-31 cve@mitre.org

Privilege Escalation Xen Debian Linux Fedora Leap

9.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

CVE Published

Oct 31, 2019 - 14:15 nvd

CRITICAL 9.8

DescriptionNVD

An issue was discovered in Xen through 4.12.x allowing 32-bit PV guest OS users to gain guest OS privileges by installing and using descriptors. There is missing descriptor table limit checking in x86 PV emulation. When emulating certain PV guest operations, descriptor table accesses are performed by the emulating code. Such accesses should respect the guest specified limits, unless otherwise guaranteed to fail in such a case. Without this, emulation of 32-bit guest user mode calls through call gates would allow guest user mode to install and then use descriptors of their choice, as long as the guest kernel did not itself install an LDT. (Most OSes don't install any LDT by default). 32-bit PV guest user mode can elevate its privileges to that of the guest kernel. Xen versions from at least 3.2 onwards are affected. Only 32-bit PV guest user mode can leverage this vulnerability. HVM, PVH, as well as 64-bit PV guests cannot leverage this vulnerability. Arm systems are unaffected.

AnalysisAI

An issue was discovered in Xen through 4.12.x allowing 32-bit PV guest OS users to gain guest OS privileges by installing and using descriptors. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Improper Privilege Management vulnerability could allow attackers to escalate privileges to gain unauthorized elevated access.

Technical ContextAI

This vulnerability is classified as Improper Privilege Management (CWE-269), which allows attackers to escalate privileges to gain unauthorized elevated access. An issue was discovered in Xen through 4.12.x allowing 32-bit PV guest OS users to gain guest OS privileges by installing and using descriptors. There is missing descriptor table limit checking in x86 PV emulation. When emulating certain PV guest operations, descriptor table accesses are performed by the emulating code. Such accesses should respect the guest specified limits, unless otherwise guaranteed to fail in such a case. Without this, emulation of 32-bit guest user mode calls through call gates would allow guest user mode to install and then use descriptors of their choice, as long as the guest kernel did not itself install an LDT. (Most OSes don't install any LDT by default). 32-bit PV guest user mode can elevate its privileges to that of the guest kernel. Xen versions from at least 3.2 onwards are affected. Only 32-bit PV guest user mode can leverage this vulnerability. HVM, PVH, as well as 64-bit PV guests cannot leverage this vulnerability. Arm systems are unaffected. Affected products include: Xen, Debian Debian Linux, Fedoraproject Fedora, Opensuse Leap. Version information: through 4.12..

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply principle of least privilege, validate privilege transitions, implement proper role separation.