Oleksandr Tyshchenko

**Name of the Vulnerable Software and Affected Versions** Linux (affected versions not specified) Xen (affected versions not specified) **Description** The issue is related to errors in resource release and a potential Denial of Service (DoS) in dom0 caused by Arm guests via PV devices. When mapping pages of guests on Arm, dom0 uses an rbtree to keep track of foreign mappings. However, updating this rbtree is not always done completely with the related lock held, resulting in a small race window. This race window can be exploited by unprivileged guests to cause inconsistencies in the rbtree, leading to crashes or the inability to perform further mappings of other guests' memory pages. **Recommendations** For Linux, at the moment, there is no information about a newer version that contains a fix for this vulnerability. For Xen, consider restricting access to PV devices for unprivileged guests to minimize the risk of exploitation until a patch is available. As a temporary workaround, consider implementing additional locking mechanisms to prevent inconsistencies in the rbtree.

**Name of the Vulnerable Software and Affected Versions** Xen versions 3.3 through 4.8.x **Description** A memory leak issue allows guest OS users to cause a denial of service by continually rebooting, resulting in ARM or x86 AMD host OS memory consumption. This occurs because certain cleanup is skipped if no pass-through device was ever assigned. **Recommendations** For Xen versions 3.3 through 4.8.x, at the moment, there is no information about a newer version that contains a fix for this issue.