Auth bypass in Xen
CVE-2018-15468
An issue was discovered in Xen through 4.11.x. The DEBUGCTL MSR contains several debugging features, some of which virtualise cleanly, but some do not. In particular, Branch Trace Store is not virtualised by the processor, and software has to be careful to configure it suitably not to lock up the core. As a result, it must only be available to fully trusted guests. Unfortunately, in the case that vPMU is disabled, all value checking was skipped, allowing the guest to choose any MSR_DEBUGCTL setting it likes. A malicious or buggy guest administrator (on Intel x86 HVM or PVH) can lock up the entire host, causing a Denial of Service.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.0 (Medium). Vector: CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.003 (24.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 24.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
Weakness classification (CWE)
References
- xenbits.xen.org/xsa/advisory-269.html (Vendor Advisory)
- security.gentoo.org/glsa/201810-06 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2018-15468?
- CVE-2018-15468 is a medium-severity vulnerability in Xen, classified under Incorrect Authorization. CVSS score: 6.0/10. Published 2018-08-17.
- How severe is CVE-2018-15468?
- Medium severity. CVSS v3 base score is 6.0 out of 10.