Jan H. Schönherr

**Name of the Vulnerable Software and Affected Versions** Linux kernel versions 3.11 through 5.10.16 **Description** The issue is related to errors in mapping grant references provided by the frontend in the Linux kernel's Xen driver. This can lead to the caller assuming successful mapping and attempting to access unmapped space, or internal state not being updated sufficiently to prevent safe recovery from errors. The estimated number of potentially affected devices worldwide is not specified. There is no information about real-world incidents where this issue was exploited. **Recommendations** For Linux kernel versions 3.11 through 5.10.16, update to a version later than 5.10.16 to resolve the issue. At the moment, there is no information about other versions that contain a fix for this vulnerability.

**Name of the Vulnerable Software and Affected Versions** Xen (affected versions not specified) XenServer (affected versions not specified) **Description** The issue is related to the `xen biovec phys mergeable` function in the `biomerge.c` driver, which has inadequate access control to certain functions. This can be exploited by a local attacker to elevate privileges, damage block device data streams, breach confidentiality, and cause a denial of service by leveraging incorrect block IO merge-ability calculation. **Recommendations** For Xen, consider restricting access to the `xen biovec phys mergeable` function in the `biomerge.c` driver until a patch is available. For XenServer, consider restricting access to the `xen biovec phys mergeable` function in the `biomerge.c` driver until a patch is available. At the moment, there is no information about a newer version that contains a fix for this vulnerability.