CVEvulnerability

CVE-2019-18420

6.5 MEDIUM Published 2019-10-31 Modified 2026-06-17 Official page ↗
Status
Modified
Published
2019-10-31
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
6.5 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0 ([email protected])
6.3 MEDIUM — AV:N/AC:M/Au:S/C:N/I:N/A:C
Weaknesses
CWE-134

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.

Affected configurations

• xen xen (<= 4.12.1) • debian debian linux 9.0 • debian debian linux 10.0 • fedoraproject fedora 29 • fedoraproject fedora 30 • fedoraproject fedora 31

Related

Weakness · CWE (1)

  • CWE-134 Use of Externally-Controlled Format String weakness

References