CVE-2019-18420
First published: Thu Oct 31 2019(Updated: )
An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to cause a denial of service via a VCPUOP_initialise hypercall. hypercall_create_continuation() is a variadic function which uses a printf-like format string to interpret its parameters. Error handling for a bad format character was done using BUG(), which crashes Xen. One path, via the VCPUOP_initialise hypercall, has a bad format character. The BUG() can be hit if VCPUOP_initialise executes for a sufficiently long period of time for a continuation to be created. Malicious guests may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen versions 4.6 and newer are vulnerable. Xen versions 4.5 and earlier are not vulnerable. Only x86 PV guests can exploit the vulnerability. HVM and PVH guests, and guests on ARM systems, cannot exploit the vulnerability.
Credit: cve@mitre.org
| Affected Software | Affected Version | How 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 |
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Reference Links
- http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00037.html
- http://www.openwall.com/lists/oss-security/2019/10/31/1
- http://xenbits.xen.org/xsa/advisory-296.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2BQKX7M2RHCWDBKNPX4KEBI3MJIH6AYZ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/I5WWPW4BSZDDW7VHU427XTVXV7ROOFFW/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/IZYATWNUGHRBG6I3TC24YHP5Y3J7I6KH/
- https://seclists.org/bugtraq/2020/Jan/21
- https://security.gentoo.org/glsa/202003-56
- https://www.debian.org/security/2020/dsa-4602
- https://xenbits.xen.org/xsa/advisory-296.html
- https://security-tracker.debian.org/tracker/CVE-2019-18420
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2BQKX7M2RHCWDBKNPX4KEBI3MJIH6AYZ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/I5WWPW4BSZDDW7VHU427XTVXV7ROOFFW/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IZYATWNUGHRBG6I3TC24YHP5Y3J7I6KH/
Frequently Asked Questions
What is the severity of CVE-2019-18420?
CVE-2019-18420 is classified as a denial of service vulnerability that impacts Xen hypervisors.
How do I fix CVE-2019-18420?
To fix CVE-2019-18420, update your Xen installation to a version that is not affected, specifically those higher than 4.12.1.
Who is affected by CVE-2019-18420?
CVE-2019-18420 affects x86 PV guest OS users operating on vulnerable versions of the Xen hypervisor.
What systems are vulnerable to CVE-2019-18420?
Systems running Xen versions up to and including 4.12.1 are vulnerable to CVE-2019-18420.
What impact does CVE-2019-18420 have on systems?
CVE-2019-18420 can lead to a denial of service condition, disrupting service for guest operating systems.
- collector/security-tracker-debian
- agent/type
- agent/remedy
- collector/mitre-cve
- source/MITRE
- agent/severity
- agent/author
- agent/last-modified-date
- agent/weakness
- agent/references
- agent/description
- agent/first-publish-date
- agent/event
- agent/source
- agent/tags
- agent/softwarecombine
- collector/nvd-index
- agent/software-canonical-lookup-request
- package-manager/debian
- vendor/xen
- canonical/xen xapi
- version/xen xapi/4.12.1
- vendor/debian
- canonical/debian
- version/debian/9.0
- version/debian/10.0
- vendor/fedoraproject
- canonical/fedora
- version/fedora/29
- version/fedora/30
- version/fedora/31