cbcvebase.
CVE-2026-53360
published 2026-07-04

CVE-2026-53360: In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Require in-GHCB scratch area if GHCB v2+ is in use As per the GHCB spec, when…

PriorityP346high8.8CVSS 3.1
AVLACLPRLUINSCCHIHAH
EPSS
0.18%
8.1th percentile
In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Require in-GHCB scratch area if GHCB v2+ is in use As per the GHCB spec, when using GHCB v2+ require the software scratch area to reside in the GHCB's shared buffer. Note, things like Page State Change (PSC) requests _rely_ on this behavior, as the guest can't provide a length when making the request, i.e. the size of the guest payload is bounded by the size of the shared buffer. Failure to force usage of the GHCB, and a slew of other flaws, lets a malicious SNP guest corrupt host kernel heap memory, and leak host heap layout information. setup_vmgexit_scratch() allocates a buffer via kvzalloc(exit_info_2), where exit_info_2 is guest-controlled. With exit_info_2=24, this yields a 24-byte allocation in kmalloc-cg-32 (32-byte slab objects). The buffer holds an 8-byte psc_hdr followed by 8-byte psc_entry structs, so only entries[0] and entries[1] are in-bounds. snp_begin_psc() validates end_entry against VMGEXIT_PSC_MAX_COUNT (253) but NOT against the actual buffer size: idx_end = hdr->end_entry; if (idx_end >= VMGEXIT_PSC_MAX_COUNT) { // checks 253, not buffer snp_complete_psc(svm, ...); return 1; } for (idx = idx_start; idx = 2 The guest sets end_entry=10+, causing the host to iterate entries[2+] which are OOB into adjacent slab objects. For each OOB entry: - The host reads 8 bytes (OOB READ / info leak oracle) - If the data passes PSC validation, __snp_complete_one_psc() writes cur_page = 1 or 512 into the entry (OOB WRITE, sev.c:3806) - If validation fails, the error response reveals whether adjacent memory is zero vs non-zero (information disclosure to guest) The guest controls allocation size (exit_info_2), entry range (cur_entry/end_entry), and can fire unlimited VMGEXITs to repeatedly hit different slab positions. By exploiting the variety of bugs, a malicious SEV-SNP guest can: - OOB read adjacent kmalloc-cg-32 objects (heap layout disclosure) - OOB write cur_page bits in

Affected

26 ranges· showing 25
VendorProductVersion rangeFixed in
linuxlinux
linuxlinux>= 4af663c2f64a8d252e690c60cf8b8abf22dc2951 < bf9ba093fbb83c0c9a3dedd50efec29424eca2fcbf9ba093fbb83c0c9a3dedd50efec29424eca2fc
linuxlinux>= 4af663c2f64a8d252e690c60cf8b8abf22dc2951 < c9b4198fbc6ed99a9da4bee9f74bb730f926c9aec9b4198fbc6ed99a9da4bee9f74bb730f926c9ae
linuxlinux>= 4af663c2f64a8d252e690c60cf8b8abf22dc2951 < b328ede59ac34e7998e1eee5e5f0cc26c2a91846b328ede59ac34e7998e1eee5e5f0cc26c2a91846
linuxlinux>= 4af663c2f64a8d252e690c60cf8b8abf22dc2951 < db3f2195d29344a3cf1e9dd9ab7f21ced7308cf7db3f2195d29344a3cf1e9dd9ab7f21ced7308cf7
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 6.10 < 6.12.936.12.93
linuxlinux_kernel>= 6.13 < 6.18.356.18.35
linuxlinux_kernel>= 6.19 < 7.0.127.0.12
ubuntulinux
ubuntulinux-aws
ubuntulinux-azure
ubuntulinux-azure-fde
ubuntulinux-gcp
ubuntulinux-gke
ubuntulinux-hwe-7.0
ubuntulinux-ibm
ubuntulinux-oem-7.0
ubuntulinux-oracle
ubuntulinux-raspi

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
vendor_redhat7.0HIGH
vendor_ubuntu7.0HIGH
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