Executive brief
A vulnerability in the Linux kernel's virtualization component (KVM) could allow a malicious guest virtual machine to compromise the host server. By exploiting flaws in how the system handles secure memory requests, an attacker could steal sensitive information from the host's memory or cause the entire system to crash. This affects servers using AMD SEV-SNP technology to run secure virtual machines.
Technical details
A vulnerability exists in the KVM SEV-SNP implementation within the Linux kernel due to insufficient validation of the software scratch area when GHCB v2+ is in use. The function `setup_vmgexit_scratch()` allows guest-controlled allocation sizes via `exit_info_2`, while `snp_begin_psc()` fails to validate the `end_entry` index against the actual allocated buffer size, checking only against a static maximum. A malicious guest can trigger out-of-bounds (OOB) reads and writes by providing a small allocation size and a large entry index. This can lead to host heap layout disclosure, heap corruption, and use-after-free conditions. The fix enforces that the scratch area must reside within the GHCB shared buffer for GHCB v2+ requests.
Affected products
- Linux Linux Kernel GHCB v2+ support in KVM SEV-SNP
Timeline
- 2026-05-01: patched: Initial patch authored by Michael Roth
- 2026-07-04: advisory: CVE published to NVD dataset