xen/arm: No memory limit for dom0less domUs The dom0less feature allows an administrator to create multiple unprivileged domains directly from Xen. Unfortunately, the memory limit from them is not set. This allow a domain to allocate memory beyond what an administrator originally configured.
CVSS Score
4.9
EPSS Score
0.003
Published
2021-08-27
inappropriate x86 IOMMU timeout detection / handling IOMMUs process commands issued to them in parallel with the operation of the CPU(s) issuing such commands. In the current implementation in Xen, asynchronous notification of the completion of such commands is not used. Instead, the issuing CPU spin-waits for the completion of the most recently issued command(s). Some of these waiting loops try to apply a timeout to fail overly-slow commands. The course of action upon a perceived timeout actually being detected is inappropriate: - on Intel hardware guests which did not originally cause the timeout may be marked as crashed, - on AMD hardware higher layer callers would not be notified of the issue, making them continue as if the IOMMU operation succeeded.
CVSS Score
7.1
EPSS Score
0.001
Published
2021-06-30
xen/arm: Boot modules are not scrubbed The bootloader will load boot modules (e.g. kernel, initramfs...) in a temporary area before they are copied by Xen to each domain memory. To ensure sensitive data is not leaked from the modules, Xen must "scrub" them before handing the page over to the allocator. Unfortunately, it was discovered that modules will not be scrubbed on Arm.
CVSS Score
5.5
EPSS Score
0.001
Published
2021-06-30
x86: TSX Async Abort protections not restored after S3 This issue relates to the TSX Async Abort speculative security vulnerability. Please see https://xenbits.xen.org/xsa/advisory-305.html for details. Mitigating TAA by disabling TSX (the default and preferred option) requires selecting a non-default setting in MSR_TSX_CTRL. This setting isn't restored after S3 suspend.
CVSS Score
6.5
EPSS Score
0.004
Published
2021-06-29
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. The effect of this is to crash the process monitoring the guest. How this affects the system depends on the structure of the toolstack. For xl, this will have no security-relevant effect: every VM has its own independent monitoring process, which contains no state. The domain in question will hang in a crashed state, but can be destroyed by `xl destroy` just like any other non-cooperating domain. For daemon-based toolstacks linked against libxl, such as libvirt, this will crash the toolstack, losing the state of any in-progress operations (localized DoS), and preventing further administrator operations unless the daemon is configured to restart automatically (system-wide DoS). If crashes "leak" resources, then repeated crashes could use up resources, also causing a system-wide DoS.
CVSS Score
5.5
EPSS Score
0.0
Published
2021-06-11
Potential speculative code store bypass in all supported CPU products, in conjunction with software vulnerabilities relating to speculative execution of overwritten instructions, may cause an incorrect speculation and could result in data leakage.
CVSS Score
5.5
EPSS Score
0.001
Published
2021-06-09
Potential floating point value injection in all supported CPU products, in conjunction with software vulnerabilities relating to speculative execution with incorrect floating point results, may cause the use of incorrect data from FPVI and may result in data leakage.
CVSS Score
5.5
EPSS Score
0.001
Published
2021-06-09
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.
CVSS Score
5.5
EPSS Score
0.001
Published
2021-02-17
An issue was discovered in Xen through 4.14.x. Neither xenstore implementation does any permission checks when reporting a xenstore watch event. A guest administrator can watch the root xenstored node, which will cause notifications for every created, modified, and deleted key. A guest administrator can also use the special watches, which will cause a notification every time a domain is created and destroyed. Data may include: number, type, and domids of other VMs; existence and domids of driver domains; numbers of virtual interfaces, block devices, vcpus; existence of virtual framebuffers and their backend style (e.g., existence of VNC service); Xen VM UUIDs for other domains; timing information about domain creation and device setup; and some hints at the backend provisioning of VMs and their devices. The watch events do not contain values stored in xenstore, only key names. A guest administrator can observe non-sensitive domain and device lifecycle events relating to other guests. This information allows some insight into overall system configuration (including the number and general nature of other guests), and configuration of other guests (including the number and general nature of other guests' devices). This information might be commercially interesting or might make other attacks easier. There is not believed to be exposure of sensitive data. Specifically, there is no exposure of VNC passwords, port numbers, pathnames in host and guest filesystems, cryptographic keys, or within-guest data.
CVSS Score
2.3
EPSS Score
0.001
Published
2020-12-15
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/<domid> are being deleted by Xen tools when a guest is destroyed, only Xenstore entries of other guests still running are affected. For example, a newly created guest domain might be able to read sensitive information that had belonged to a previously existing guest domain. Both Xenstore implementations (C and Ocaml) are vulnerable.
CVSS Score
8.8
EPSS Score
0.001
Published
2020-12-15