USN-8887-1: Linux kernel update fixes flaws, including an SEV-SNP guest memory issue

Notice USN-8887-1, published on October 6, 2026 in the Ubuntu Security feed, describes a Linux kernel update that fixes numerous flaws. The highlight is CVE-2023-20585: some AMD processors were found not to perform Reverse Map Table (RMP) checks correctly when the IOMMU accessed certain host buffers. A local attacker with access to the hypervisor could possibly use this to trigger an out-of-bounds condition and compromise the memory integrity of SEV-SNP guests. The notice also reports several other security problems that an attacker could possibly use to compromise the system, with fixes in areas such as ARM64, NVDIMM, the crypto API, the Intel NPU driver, ACPI, Bluetooth, TPM, IOMMU, DMA, PCI, USB, networking, storage, filesystems, BPF, memory and KVM. The list includes dozens of CVE identifiers, among them CVE-2026-64349 and CVE-2026-68188. The text is a machine translation of the original, so technical terms should be checked against the official notice. To consult and verify, open the Ubuntu security notices page and search for USN-8887-1, where you will find the full CVE list, the affected package versions and update instructions.