An issue was discovered in Xen 4.14.x. There is a missing unlock in the XENMEM_acquire_resource error path. The RCU (Read, Copy, Update) mechanism is a synchronisation primitive. A buggy error path in the XENMEM_acquire_resource exits without releasing an RCU reference, which is conceptually similar to forgetting to unlock a spinlock. A buggy or malicious HVM stubdomain can cause an RCU reference to be leaked. This causes subsequent administration operations, (e.g., CPU offline) to livelock, resulting in a host Denial of Service. The buggy codepath has been present since Xen 4.12. Xen 4.14 and later are vulnerable to the DoS. The side effects are believed to be benign on Xen 4.12 and 4.13, but patches are provided nevertheless. The vulnerability can generally only be exploited by x86 HVM VMs, as these are generally the only type of VM that have a Qemu stubdomain. x86 PV and PVH domains, as well as ARM VMs, typically don't use a stubdomain. Only VMs using HVM stubdomains can exploit the vulnerability. VMs using PV stubdomains, or with emulators running in dom0, cannot exploit the vulnerability.
Published 2020-09-23 22:15:13
Updated 2022-12-02 20:13:35
Source MITRE
View at NVD,   CVE.org
Vulnerability category: Denial of service

Exploit prediction scoring system (EPSS) score for CVE-2020-25598

Probability of exploitation activity in the next 30 days: 0.05%

Percentile, the proportion of vulnerabilities that are scored at or less: ~ 12 % EPSS Score History EPSS FAQ

CVSS scores for CVE-2020-25598

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source
2.1
LOW AV:L/AC:L/Au:N/C:N/I:N/A:P
3.9
2.9
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-2020-25598

  • The code contains a control flow path that does not reflect the algorithm that the path is intended to implement, leading to incorrect behavior any time this path is navigated.
    Assigned by: nvd@nist.gov (Primary)

References for CVE-2020-25598

Products affected by CVE-2020-25598

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