medium
5.5
Advisory Published
Updated

CVE-2020-25601

First published: Wed Sep 23 2020(Updated: )

An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions are vulnerable in principle. Whether versions 4.3 and older are vulnerable depends on underlying hardware characteristics.

Credit: cve@mitre.org cve@mitre.org

Affected SoftwareAffected VersionHow to fix
Xen xen-unstable<=4.14.0
Debian Debian Linux=10.0
Fedoraproject Fedora=31
Fedoraproject Fedora=32
Fedoraproject Fedora=33
openSUSE=15.2
debian/xen
4.14.6-1
4.14.5+94-ge49571868d-1
4.17.3+10-g091466ba55-1~deb12u1
4.17.5+23-ga4e5191dc0-1
4.19.1-1

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Reference Links

Frequently Asked Questions

  • What is the vulnerability ID of this issue?

    The vulnerability ID is CVE-2020-25601.

  • What is the severity of CVE-2020-25601?

    The severity of CVE-2020-25601 is not mentioned in the provided information.

  • What is the affected software?

    The affected software is Xen versions up to 4.14.x.

  • How does the vulnerability occur?

    The vulnerability occurs due to a lack of preemption in evtchn_reset() / evtchn_destroy().

  • How do I fix this vulnerability?

    To fix this vulnerability, update Xen to version 4.11.3+24- or apply the recommended patch for the specific distribution/operating system.

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