critical
9.8
CWE
269
Advisory Published
Updated

CVE-2019-18425

First published: Thu Oct 31 2019(Updated: )

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.

Credit: cve@mitre.org

Affected SoftwareAffected VersionHow to fix
debian/xen
4.11.4+107-gef32c7afa2-1
4.14.6-1
4.14.5+94-ge49571868d-1
4.17.2+76-ge1f9cb16e2-1~deb12u1
4.17.2+76-ge1f9cb16e2-1
Xen XAPI<=4.12.1
Debian=9.0
Debian=10.0
Fedora=29
Fedora=30
Fedora=31
SUSE Linux=15.0

Remedy

http://xenbits.xen.org/xsa/advisory-298.html

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Reference Links

Frequently Asked Questions

  • What is the severity of CVE-2019-18425?

    CVE-2019-18425 is classified as a high severity vulnerability due to the potential for privilege escalation in 32-bit PV guest OS environments.

  • How do I fix CVE-2019-18425?

    To mitigate CVE-2019-18425, users should update Xen to versions 4.12.2 or higher, or apply the specified patches according to their distribution.

  • Who is affected by CVE-2019-18425?

    CVE-2019-18425 affects users of Xen versions up to 4.12.1 who are running 32-bit paravirtualized guest operating systems.

  • What can an attacker do with CVE-2019-18425?

    An attacker exploiting CVE-2019-18425 can gain unrestricted access to the guest OS, leading to unauthorized actions and potential system compromise.

  • Is CVE-2019-18425 specific to certain operating systems?

    Yes, CVE-2019-18425 specifically impacts paravirtualized guest OS installations on Xen across various distributions, including Debian and Fedora.

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