CVE-2019-18420

Advisory lineage Upstream: 0 Downstream: 13
Modified
Published: 31 Oct 2019, 13:30
Last modified:05 Aug 2024, 01:54

Vulnerability Summary

Overall Risk (default)
medium
27/100
CVSS Score
6.5 MEDIUM
v3.1 (nvd)
EPSS Score
4.05% LOW
4% probability -0.21%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

31 Oct 2019, 13:30
Published
Vulnerability first disclosed
05 Aug 2024, 01:54
Last Modified
Vulnerability information updated

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 Metrics

  • v3.1•MEDIUM•Score: 6.5CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  • v2.0•MEDIUM•Score: 6.3AV:N/AC:M/Au:S/C:N/I:N/A:C

EPSS Trends

Current EPSS score: 4.05%• Percentile: 89%

Techniques & Countermeasures

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

    The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

Affected Systems

  • debian•debian_linux

    9.0 | 10.0

  • fedoraproject•fedora

    29 | 30 | 31

  • xen•xen

    ≤ 4.12.1

References (9)