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Vulnerability · Published Jan 26, 2021 · Assigned by mitre

CVE-2021-3308

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 36% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)5.5Medium
Exploit odds (30 days)0.4%top 63.6% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

An issue was discovered in Xen 4.12.3 through 4.12.4 and 4.13.1 through 4.14.x. An x86 HVM guest with PCI pass through devices can force the allocation of all IDT vectors on the system by rebooting itself with MSI or MSI-X capabilities enabled and entries setup. Such reboots will leak any vectors used by the MSI(-X) entries that the guest might had enabled, and hence will lead to vector exhaustion on the system, not allowing further PCI pass through devices to work properly. HVM guests with PCI pass through devices can mount a Denial of Service (DoS) attack affecting the pass through of PCI devices to other guests or the hardware domain. In the latter case, this would affect the entire host.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.20xen4.14.1-r2ALPINE-CVE-2021-3308
Alpine:v3.21xen4.14.1-r2ALPINE-CVE-2021-3308
Alpine:v3.22xen4.14.1-r2ALPINE-CVE-2021-3308
Alpine:v3.23xen4.14.1-r2ALPINE-CVE-2021-3308
Alpine:v3.24xen4.14.1-r2ALPINE-CVE-2021-3308
Debian:12xen4.14.1+11-gb0b734a8b3-1DEBIAN-CVE-2021-3308
Debian:13xen4.14.1+11-gb0b734a8b3-1DEBIAN-CVE-2021-3308
Debian:14xen4.14.1+11-gb0b734a8b3-1DEBIAN-CVE-2021-3308

Affected products (as reported)

VendorProductVersions
n/a n/a n/a

References