CVE-2019-18420
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…
Does this matter?
Lower severity and a low EPSS score (2.52%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 2.52% probability · 84th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-134
- Affected
- xen/xen · debian/debian linux · fedoraproject/fedora
- Source
- cve@mitre.org
References
- http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00037.htmlBroken Link, Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2019/10/31/1Mailing List, Patch, Third Party Advisory
- http://xenbits.xen.org/xsa/advisory-296.htmlPatch, Vendor Advisory
- 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/
- https://seclists.org/bugtraq/2020/Jan/21Mailing List, Third Party Advisory
- https://security.gentoo.org/glsa/202003-56Third Party Advisory
- https://www.debian.org/security/2020/dsa-4602Third Party Advisory
- http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00037.htmlBroken Link, Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2019/10/31/1Mailing List, Patch, Third Party Advisory
- http://xenbits.xen.org/xsa/advisory-296.htmlPatch, Vendor Advisory
- 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/
- https://seclists.org/bugtraq/2020/Jan/21Mailing List, Third Party Advisory
- https://security.gentoo.org/glsa/202003-56Third Party Advisory
- https://www.debian.org/security/2020/dsa-4602Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.