
CVE-2021-28689
https://notcve.org/view.php?id=CVE-2021-28689
11 Jun 2021 — 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 ... • https://xenbits.xenproject.org/xsa/advisory-370.txt • CWE-212: Improper Removal of Sensitive Information Before Storage or Transfer •

CVE-2021-27379 – Debian Security Advisory 4888-1
https://notcve.org/view.php?id=CVE-2021-27379
18 Feb 2021 — 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 DM... • http://www.openwall.com/lists/oss-security/2021/02/23/1 •

CVE-2021-26933 – Debian Security Advisory 4888-1
https://notcve.org/view.php?id=CVE-2021-26933
17 Feb 2021 — 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 •

CVE-2021-3308 – Gentoo Linux Security Advisory 202107-30
https://notcve.org/view.php?id=CVE-2021-3308
26 Jan 2021 — 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... • http://www.openwall.com/lists/oss-security/2021/01/26/4 •

CVE-2020-29486 – Debian Security Advisory 4812-1
https://notcve.org/view.php?id=CVE-2020-29486
15 Dec 2020 — An issue was discovered in Xen through 4.14.x. Nodes in xenstore have an ownership. In oxenstored, a owner could give a node away. However, node ownership has quota implications. Any guest can run another guest out of quota, or create an unbounded number of nodes owned by dom0, thus running xenstored out of memory A malicious guest administrator can cause a denial of service against a specific guest or against the whole host. • https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2C6M6S3CIMEBACH6O7V4H2VDANMO6TVA • CWE-770: Allocation of Resources Without Limits or Throttling •

CVE-2020-29481 – Debian Security Advisory 4812-1
https://notcve.org/view.php?id=CVE-2020-29481
15 Dec 2020 — An issue was discovered in Xen through 4.14.x. Access rights of Xenstore nodes are per domid. Unfortunately, existing granted access rights are not removed when a domain is being destroyed. This means that a new domain created with the same domid will inherit the access rights to Xenstore nodes from the previous domain(s) with the same domid. Because all Xenstore entries of a guest below /local/domain/

CVE-2020-29485 – Debian Security Advisory 4812-1
https://notcve.org/view.php?id=CVE-2020-29485
15 Dec 2020 — An issue was discovered in Xen 4.6 through 4.14.x. When acting upon a guest XS_RESET_WATCHES request, not all tracking information is freed. A guest can cause unbounded memory usage in oxenstored. This can lead to a system-wide DoS. Only systems using the Ocaml Xenstored implementation are vulnerable. • https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2C6M6S3CIMEBACH6O7V4H2VDANMO6TVA • CWE-401: Missing Release of Memory after Effective Lifetime •

CVE-2020-29484 – Debian Security Advisory 4812-1
https://notcve.org/view.php?id=CVE-2020-29484
15 Dec 2020 — An issue was discovered in Xen through 4.14.x. When a Xenstore watch fires, the xenstore client that registered the watch will receive a Xenstore message containing the path of the modified Xenstore entry that triggered the watch, and the tag that was specified when registering the watch. Any communication with xenstored is done via Xenstore messages, consisting of a message header and the payload. The payload length is limited to 4096 bytes. Any request to xenstored resulting in a response with a payload l... • https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2C6M6S3CIMEBACH6O7V4H2VDANMO6TVA • CWE-476: NULL Pointer Dereference •

CVE-2020-29483 – Debian Security Advisory 4812-1
https://notcve.org/view.php?id=CVE-2020-29483
15 Dec 2020 — An issue was discovered in Xen through 4.14.x. Xenstored and guests communicate via a shared memory page using a specific protocol. When a guest violates this protocol, xenstored will drop the connection to that guest. Unfortunately, this is done by just removing the guest from xenstored's internal management, resulting in the same actions as if the guest had been destroyed, including sending an @releaseDomain event. @releaseDomain events do not say that the guest has been removed. • https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2C6M6S3CIMEBACH6O7V4H2VDANMO6TVA • CWE-416: Use After Free •

CVE-2020-29482 – Debian Security Advisory 4812-1
https://notcve.org/view.php?id=CVE-2020-29482
15 Dec 2020 — An issue was discovered in Xen through 4.14.x. A guest may access xenstore paths via absolute paths containing a full pathname, or via a relative path, which implicitly includes /local/domain/$DOMID for their own domain id. Management tools must access paths in guests' namespaces, necessarily using absolute paths. oxenstored imposes a pathname limit that is applied solely to the relative or absolute path specified by the client. Therefore, a guest can create paths in its own namespace which are too long for... • https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2C6M6S3CIMEBACH6O7V4H2VDANMO6TVA • CWE-426: Untrusted Search Path •