Privilege escalation in Xen
CVE-2021-28692
inappropriate x86 IOMMU timeout detection / handling IOMMUs process commands issued to them in parallel with the operation of the CPU(s) issuing such commands. In the current implementation in Xen, asynchronous notification of the completion of such commands is not used. Instead, the issuing CPU spin-waits for the completion of the most recently issued command(s). Some of these waiting loops try to apply a timeout to fail overly-slow commands. The course of action upon a perceived timeout actually being detected is inappropriate: - on Intel hardware guests which did not originally cause the timeout may be marked as crashed, - on AMD hardware higher layer callers would not be notified of the issue, making them continue as if the IOMMU operation succeeded.
Vulnerability class: Privilege Escalation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H.
EPSS exploit prediction
EPSS: 0.003 (19.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.3% 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
- Xen — versions 4.13.x, 4.14.x, 4.15.x
Weakness classification (CWE)
References
- xenbits.xenproject.org/xsa/advisory-373.txt (Vendor Advisory)
- security.gentoo.org/glsa/202107-30 (vendor-advisory, Third Party Advisory, Mitigation)
Frequently asked questions
- What is CVE-2021-28692?
- CVE-2021-28692 is a high-severity vulnerability in Xen, classified under Improper Privilege Management. CVSS score: 7.1/10. Published 2021-06-30.
- How severe is CVE-2021-28692?
- High severity. CVSS v3 base score is 7.1 out of 10.