{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53360","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-06-09T07:44:35.400Z","datePublished":"2026-07-04T11:53:58.657Z","dateUpdated":"2026-07-04T11:53:58.657Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-07-04T11:53:58.657Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Require in-GHCB scratch area if GHCB v2+ is in use\n\nAs per the GHCB spec, when using GHCB v2+ require the software scratch area\nto reside in the GHCB's shared buffer.  Note, things like Page State Change\n(PSC) requests _rely_ on this behavior, as the guest can't provide a length\nwhen making the request, i.e. the size of the guest payload is bounded by\nthe size of the shared buffer.\n\nFailure to force usage of the GHCB, and a slew of other flaws, lets a\nmalicious SNP guest corrupt host kernel heap memory, and leak host heap\nlayout information.\n\nsetup_vmgexit_scratch() allocates a buffer via kvzalloc(exit_info_2),\nwhere exit_info_2 is guest-controlled. With exit_info_2=24, this yields\na 24-byte allocation in kmalloc-cg-32 (32-byte slab objects). The buffer\nholds an 8-byte psc_hdr followed by 8-byte psc_entry structs, so only\nentries[0] and entries[1] are in-bounds.\n\nsnp_begin_psc() validates end_entry against VMGEXIT_PSC_MAX_COUNT (253)\nbut NOT against the actual buffer size:\n\n      idx_end = hdr->end_entry;\n\n      if (idx_end >= VMGEXIT_PSC_MAX_COUNT) {   // checks 253, not buffer\n          snp_complete_psc(svm, ...);\n          return 1;\n      }\n\n      for (idx = idx_start; idx <= idx_end; idx++) {\n          entry_start = entries[idx];           // OOB when idx >= 2\n\nThe guest sets end_entry=10+, causing the host to iterate entries[2+]\nwhich are OOB into adjacent slab objects. For each OOB entry:\n\n  - The host reads 8 bytes (OOB READ / info leak oracle)\n  - If the data passes PSC validation, __snp_complete_one_psc() writes\n    cur_page = 1 or 512 into the entry (OOB WRITE, sev.c:3806)\n  - If validation fails, the error response reveals whether adjacent\n    memory is zero vs non-zero (information disclosure to guest)\n\nThe guest controls allocation size (exit_info_2), entry range\n(cur_entry/end_entry), and can fire unlimited VMGEXITs to repeatedly\nhit different slab positions.\n\nBy exploiting the variety of bugs, a malicious SEV-SNP guest can:\n    - OOB read adjacent kmalloc-cg-32 objects (heap layout disclosure)\n    - OOB write cur_page bits into adjacent objects (heap corruption)\n    - Trigger use-after-free conditions across VMGEXITs\n\nE.g. with KASAN enabled, a single insmod of the PoC guest module\nproduces 73 KASAN reports:\n\n    BUG: KASAN: slab-out-of-bounds in snp_begin_psc+0x126/0x890\n    Read of size 8 at addr ffff888219ffb5e0 by task qemu-system-x86/2199\n\n    BUG: KASAN: slab-out-of-bounds in snp_begin_psc+0x468/0x890\n    Write of size 8 at addr ffff888351566648 by task qemu-system-x86/2199\n\n    The buggy address belongs to the object at ffff888XXXXXXXXX\n     which belongs to the cache kmalloc-cg-32 of size 32\n    The buggy address is located N bytes to the right of\n     allocated 32-byte region [ffff888XXXXXXXXX, ffff888XXXXXXXXX)\n\n  Breakdown:\n    62 slab-out-of-bounds (reads + writes past allocation)\n     7 slab-use-after-free\n     4 use-after-free\n\nAll credit to Stan for the wonderful description and reproducer!\n\n[sean: write changelog]"}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/sev.c"],"versions":[{"version":"4af663c2f64a8d252e690c60cf8b8abf22dc2951","lessThan":"bf9ba093fbb83c0c9a3dedd50efec29424eca2fc","status":"affected","versionType":"git"},{"version":"4af663c2f64a8d252e690c60cf8b8abf22dc2951","lessThan":"c9b4198fbc6ed99a9da4bee9f74bb730f926c9ae","status":"affected","versionType":"git"},{"version":"4af663c2f64a8d252e690c60cf8b8abf22dc2951","lessThan":"b328ede59ac34e7998e1eee5e5f0cc26c2a91846","status":"affected","versionType":"git"},{"version":"4af663c2f64a8d252e690c60cf8b8abf22dc2951","lessThan":"db3f2195d29344a3cf1e9dd9ab7f21ced7308cf7","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/sev.c"],"versions":[{"version":"6.10","status":"affected"},{"version":"0","lessThan":"6.10","status":"unaffected","versionType":"semver"},{"version":"6.12.93","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.35","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.12","lessThanOrEqual":"7.0.*","status":"unaffected","versionType":"semver"},{"version":"7.1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"6.12.93"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"6.18.35"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"7.0.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"7.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/bf9ba093fbb83c0c9a3dedd50efec29424eca2fc"},{"url":"https://git.kernel.org/stable/c/c9b4198fbc6ed99a9da4bee9f74bb730f926c9ae"},{"url":"https://git.kernel.org/stable/c/b328ede59ac34e7998e1eee5e5f0cc26c2a91846"},{"url":"https://git.kernel.org/stable/c/db3f2195d29344a3cf1e9dd9ab7f21ced7308cf7"}],"title":"KVM: SEV: Require in-GHCB scratch area if GHCB v2+ is in use","x_generator":{"engine":"bippy-1.2.0"}}}}