CVE-2020-29566
First published: Tue Dec 15 2020(Updated: )
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.
Credit: cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| debian/xen | 4.11.4+107-gef32c7afa2-1 4.14.6-1 4.14.5+94-ge49571868d-1 4.17.1+2-gb773c48e36-1 4.17.2+55-g0b56bed864-1 | |
| Xen xen-unstable | <=4.14.0 | |
| Debian | =10.0 | |
| Fedora | =32 | |
| Fedora | =33 |
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Reference Links
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2C6M6S3CIMEBACH6O7V4H2VDANMO6TVA/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/OBLV6L6Q24PPQ2CRFXDX4Q76KU776GKI/
- https://security.gentoo.org/glsa/202107-30
- https://www.debian.org/security/2020/dsa-4812
- https://xenbits.xenproject.org/xsa/advisory-348.html
- https://xenbits.xen.org/xsa/advisory-348.html
- https://security-tracker.debian.org/tracker/CVE-2020-29566
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OBLV6L6Q24PPQ2CRFXDX4Q76KU776GKI/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2C6M6S3CIMEBACH6O7V4H2VDANMO6TVA/
Frequently Asked Questions
What is the severity of CVE-2020-29566?
The severity of CVE-2020-29566 is generally considered to be high due to potential security implications for x86 HVM guests.
How do I fix CVE-2020-29566?
To fix CVE-2020-29566, update to a patched version of Xen, such as 4.11.4+107-gef32c7afa2-1 or later.
What versions of Xen are affected by CVE-2020-29566?
CVE-2020-29566 affects Xen versions up to and including 4.14.0.
What types of systems are impacted by CVE-2020-29566?
CVE-2020-29566 impacts systems running Xen on x86 architectures.
Is CVE-2020-29566 relevant for Debian and Fedora users?
Yes, CVE-2020-29566 is relevant for users of Debian versions like 10.0 and Fedora versions 32 and 33 that use affected Xen packages.
- collector/security-tracker-debian
- agent/type
- collector/mitre-cve
- source/MITRE
- agent/last-modified-date
- agent/severity
- agent/remedy
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- agent/author
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- agent/first-publish-date
- agent/event
- agent/description
- agent/source
- agent/softwarecombine
- agent/tags
- collector/nvd-index
- agent/software-canonical-lookup-request
- package-manager/debian
- vendor/xen
- canonical/xen xen-unstable
- version/xen xen-unstable/4.14.0
- vendor/debian
- canonical/debian
- version/debian/10.0
- vendor/fedoraproject
- canonical/fedora
- version/fedora/32
- version/fedora/33