CVSS: 5.5EPSS: 0%CPEs: 2EXPL: 0CVE-2021-28687
https://notcve.org/view.php?id=CVE-2021-28687
HVM soft-reset crashes toolstack libxl requires all data structures passed across its public interface to be initialized before use and disposed of afterwards by calling a specific set of functions. Many internal data structures also require this initialize / dispose discipline, but not all of them. When the "soft reset" feature was implemented, the libxl__domain_suspend_state structure didn't require any initialization or disposal. At some point later, an initialization function was introduced for the structure; but the "soft reset" path wasn't refactored to call the initialization function. When a guest nwo initiates a "soft reboot", uninitialized data structure leads to an assert() when later code finds the structure in an unexpected state. • https://security.gentoo.org/glsa/202107-30 https://xenbits.xenproject.org/xsa/advisory-368.txt • CWE-909: Missing Initialization of Resource •
CVSS: 5.5EPSS: 0%CPEs: 1EXPL: 0CVE-2021-28689
https://notcve.org/view.php?id=CVE-2021-28689
x86: Speculative vulnerabilities with bare (non-shim) 32-bit PV guests 32-bit x86 PV guest kernels run in ring 1. At the time when Xen was developed, this area of the i386 architecture was rarely used, which is why Xen was able to use it to implement paravirtualisation, Xen's novel approach to virtualization. In AMD64, Xen had to use a different implementation approach, so Xen does not use ring 1 to support 64-bit guests. With the focus now being on 64-bit systems, and the availability of explicit hardware support for virtualization, fixing speculation issues in ring 1 is not a priority for processor companies. Indirect Branch Restricted Speculation (IBRS) is an architectural x86 extension put together to combat speculative execution sidechannel attacks, including Spectre v2. • https://xenbits.xenproject.org/xsa/advisory-370.txt • CWE-212: Improper Removal of Sensitive Information Before Storage or Transfer •
CVSS: 7.8EPSS: 0%CPEs: 2EXPL: 0CVE-2021-27379
https://notcve.org/view.php?id=CVE-2021-27379
An issue was discovered in Xen through 4.11.x, allowing x86 Intel HVM guest OS users to achieve unintended read/write DMA access, and possibly cause a denial of service (host OS crash) or gain privileges. This occurs because a backport missed a flush, and thus IOMMU updates were not always correct. NOTE: this issue exists because of an incomplete fix for CVE-2020-15565. Se detectó un problema en Xen versiones hasta 4.11.x, permitiendo a usuarios del Sistema Operativo invitado x86 Intel HVM obtener acceso DMA de lectura y escritura no previsto y posiblemente causar una denegación de servicio (bloqueo del Sistema Operativo host) o alcanzar privilegios. Esto ocurre porque un backport no se descargó y, por lo tanto, las actualizaciones de IOMMU no siempre fueron correctas. • http://www.openwall.com/lists/oss-security/2021/02/23/1 http://xenbits.xen.org/xsa/advisory-366.html https://www.debian.org/security/2021/dsa-4888 https://xenbits.xen.org/xsa/advisory-366.html •
CVSS: 5.5EPSS: 0%CPEs: 4EXPL: 0CVE-2021-26933
https://notcve.org/view.php?id=CVE-2021-26933
An issue was discovered in Xen 4.9 through 4.14.x. On Arm, a guest is allowed to control whether memory accesses are bypassing the cache. This means that Xen needs to ensure that all writes (such as the ones during scrubbing) have reached the memory before handing over the page to a guest. Unfortunately, the operation to clean the cache is happening before checking if the page was scrubbed. Therefore there is no guarantee when all the writes will reach the memory. • http://xenbits.xen.org/xsa/advisory-364.html https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4GELN5E6MDR5KQBJF5M5COUUED3YFZTD https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EOAJBVAVR6RSCUCHNXPVSNRPSFM7INMP https://www.debian.org/security/2021/dsa-4888 •
CVSS: 5.5EPSS: 0%CPEs: 4EXPL: 0CVE-2021-3308
https://notcve.org/view.php?id=CVE-2021-3308
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. • http://www.openwall.com/lists/oss-security/2021/01/26/4 http://xenbits.xen.org/xsa/advisory-360.html https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/S5C42TMQYB6SDVT2MPFEWY65A6RSUVBN https://security.gentoo.org/glsa/202107-30 •