An issue was discovered in Xen through 4.14.x. When they require assistance from the device model, x86 HVM guests must be temporarily de-scheduled. The device model will signal Xen when it has completed its operation, via an event channel, so that the relevant vCPU is rescheduled. If the device model were to signal Xen without having actually completed the operation, the de-schedule / re-schedule cycle would repeat. If, in addition, Xen is resignalled very quickly, the re-schedule may occur before the de-schedule was fully complete, triggering a shortcut. This potentially repeating process uses ordinary recursive function calls, and thus could result in a stack overflow. A malicious or buggy stubdomain serving a HVM guest can cause Xen to crash, resulting in a Denial of Service (DoS) to the entire host. Only x86 systems are affected. Arm systems are not affected. Only x86 stubdomains serving HVM guests can exploit the vulnerability.
Published 2020-12-15 17:15:15
Updated 2021-12-10 02:00:01
Source MITRE
View at NVD,   CVE.org
Vulnerability category: Denial of service

Exploit prediction scoring system (EPSS) score for CVE-2020-29566

0.05%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 16 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2020-29566

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
4.9
MEDIUM AV:L/AC:L/Au:N/C:N/I:N/A:C
3.9
6.9
NIST
5.5
MEDIUM CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
1.8
3.6
NIST

CWE ids for CVE-2020-29566

  • The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
    Assigned by: nvd@nist.gov (Primary)

References for CVE-2020-29566

Products affected by CVE-2020-29566

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