CVE-2020-25604

4.7 MEDIUM 0.3% exploit odds Fix listed

What it is

An issue was discovered in Xen through 4.14.x. There is a race condition when migrating timers between x86 HVM vCPUs. When migrating timers of x86 HVM guests between its vCPUs, the locking model used allows for a second vCPU of the same guest (also operating on the timers) to release a lock that it didn't acquire. The most likely effect of the issue is a hang or crash of the hypervisor, i.e., a Denial of Service (DoS). All versions of Xen are affected. Only x86 systems are vulnerable. Arm systems are not vulnerable. Only x86 HVM guests can leverage the vulnerability. x86 PV and PVH cannot leverage the vulnerability. Only guests with more than one vCPU can exploit the vulnerability.

At a glance

Exploitability: Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.
Exploit odds: 0.3% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2020-09-23 22:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 03:06 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.3% in the next 30 days (EPSS).
Severity: 4.7 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2020-09-23 22:15 UTC
Last modified: 2026-06-17 03:06 UTC
Exploit probability: 0.3% · EPSS, next 30 days
Weakness: CWE-362 · Race condition
Record status: Modified

Affected

Xen ≤ 4.14.0
Fedoraproject Fedora 31
Fedoraproject Fedora 32
Fedoraproject Fedora 33
Debian Linux 10.0
Opensuse Leap 15.2

Attack profile CVSS 3.1 · 4.7

Attack vector: Local
Complexity: High
Privileges needed: Low
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2020-25604.md and follow it. Check whether this project is affected by CVE-2020-25604. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record