CVE-2021-28702 Use after free in xen
A use-after-free vulnerability in Xen allows guest users to cause memory corruption or execute code via improper deassignment of PCI devices with RMRRs.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-28702?
CVE-2021-28702 is a high-severity use after free vulnerability in Debian Debian Linux, published on 6 Oct 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
PCI devices with RMRRs not deassigned correctly Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, "RMRR"). These are typically used for platform tasks such as legacy USB emulation. If such a device is passed through to a guest, then on guest shutdown the device is not properly deassigned. The IOMMU configuration for these devices which are not properly deassigned ends up pointing to a freed data structure, including the IO Pagetables. Subsequent DMA or interrupts from the device will have unpredictable behaviour, ranging from IOMMU faults to memory corruption.
Weakness: CWE-269
Which versions are affected by CVE-2021-28702?
It affects 3 products.
Linux distribution packages (1)
xen openSUSE:Tumbleweed | All versions | 4.16.0_01-1.1 |
Products include Debian Debian Linux, Fedoraproject Fedora, Xen Xen.
How do I fix CVE-2021-28702?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2021-28702 being exploited?
There is no known exploitation of CVE-2021-28702 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as ALPINE-CVE-2021-28702, DEBIAN-CVE-2021-28702, GHSA-pcvc-mv96-7jh6, UBUNTU-CVE-2021-28702, openSUSE-SU-2024:11624-1.