Vulnerability · Published Dec 15, 2020 · Assigned by mitre
CVE-2020-29566
Medium 5.5
In plain English
A medium-severity security flaw in the xen package (Alpine). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | xen | 4.14.1-r0 | ALPINE-CVE-2020-29566 |
| Alpine:v3.21 | xen | 4.14.1-r0 | ALPINE-CVE-2020-29566 |
| Alpine:v3.22 | xen | 4.14.1-r0 | ALPINE-CVE-2020-29566 |
| Alpine:v3.23 | xen | 4.14.1-r0 | ALPINE-CVE-2020-29566 |
| Alpine:v3.24 | xen | 4.14.1-r0 | ALPINE-CVE-2020-29566 |
| Debian:12 | xen | 4.14.0+88-g1d1d1f5391-1 | DEBIAN-CVE-2020-29566 |
| Debian:13 | xen | 4.14.0+88-g1d1d1f5391-1 | DEBIAN-CVE-2020-29566 |
| Debian:14 | xen | 4.14.0+88-g1d1d1f5391-1 | DEBIAN-CVE-2020-29566 |
Affected products (as reported)
References
- https://xenbits.xenproject.org/xsa/advisory-348.html x_refsource_MISC
- DSA-4812 vendor-advisory, x_refsource_DEBIAN
- FEDORA-2020-64859a826b vendor-advisory, x_refsource_FEDORA
- FEDORA-2020-df772b417b vendor-advisory, x_refsource_FEDORA
- GLSA-202107-30 vendor-advisory, x_refsource_GENTOO