{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-63807 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-63807 is a high-severity memory corruption vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-63807 and fix it if it is affected.\n\nWhat it is: CVE-2026-63807 is a high-severity memory corruption vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-63807 in the wild and no public exploit code.\n\nAffected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-63807/ (Markdown: https://insights.sbomify.com/CVE-2026-63807/index.md)","id":"CVE-2026-63807","markdown":"https://insights.sbomify.com/CVE-2026-63807/index.md","name":"CVE-2026-63807","record":{"aliases":["BELL-CVE-2026-63807","DEBIAN-CVE-2026-63807","GHSA-xxf6-pvjr-qhj4","ROOT-OS-UBUNTU-2204-CVE-2026-63807","UBUNTU-CVE-2026-63807"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service","code_execution"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel KVM","requires_auth":"low_privilege","summary":"A guest VM can trigger an out-of-bounds memory access in the Linux kernel KVM module, causing a host crash or potential code execution.","user_interaction":"not_required","vuln_class":"memory_corruption"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":8.8,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-125","name":"Out-of-bounds Read"},{"id":"CWE-787","name":"Out-of-bounds Write"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86/mmu: Ensure hugepage is in by slot before checking max mapping level\n\nWhen recovering hugepages in the shadow MMU, verify that the base gfn of\nthe shadow page is actually contained within the target memslot, *before*\nquerying the max mapping level given the shadow page's gfn.  Failure to\npre-check the validity of the gfn can lead to an out-of-bounds access to\nthe slot's lpage_info (which typically manifests as a host #PF because the\nlpage_info is vmalloc'd) if the guest creates a hugepage mapping (in its\nPTEs) that extends \"below\" the bounds of a memslot.\n\nWhen faulting in memory for a guest, and the size of the guest mapping is\ngreater than KVM's (current) max mapping, then KVM will create a \"direct\"\nshadow page (direct in that there are no gPTEs to shadow, and so the target\ngfn is a direct calculation given the base gfn of the shadow page).  The\nhugepage recovery flow looks for such direct shadow pages, as forcing 4KiB\nmappings when dirty logging generates the guest \u003e host mapping size case.\nWhen the 4KiB restriction is lifted, then KVM can replace the shadow page\nwith a hugepage.\n\nBut if KVM originally used a smaller mapping than the guest because the\nrange of memory covered by the guest hugepage exceeds the bounds of a\nmemslot, then KVM will link a direct shadow page with a gfn that is outside\nthe bounds of the memslot being used to fault in memory.  The rmap entry\nadded for the leaf mapping is correct and within bounds, but the gfn of the\nleaf SPTE's parent shadow page will be out of bounds.\n\n  BUG: unable to handle page fault for address: ffffc90000806ffc\n  #PF: supervisor read access in kernel mode\n  #PF: error_code(0x0000) - not-present page\n  PGD 100000067 P4D 100000067 PUD 1002a7067 PMD 10612f067 PTE 0\n  Oops: Oops: 0000 [#1] SMP\n  CPU: 13 UID: 1000 PID: 757 Comm: mmu_stress_test Not tainted 7.1.0-rc1-48ce1e26eace-x86_pir_to_irr_comments-vm #341 PREEMPT\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n  RIP: 0010:kvm_mmu_max_mapping_level+0x79/0x2b0 [kvm]\n  Call Trace:\n   \u003cTASK\u003e\n   kvm_mmu_recover_huge_pages+0x21b/0x320 [kvm]\n   kvm_set_memslot+0x1ee/0x590 [kvm]\n   kvm_set_memory_region.part.0+0x3a1/0x4d0 [kvm]\n   kvm_vm_ioctl+0x9bf/0x15d0 [kvm]\n   __x64_sys_ioctl+0x8a/0xd0\n   do_syscall_64+0xb7/0xbb0\n   entry_SYSCALL_64_after_hwframe+0x4b/0x53\n  RIP: 0033:0x7f21c0f1a9bf\n   \u003c/TASK\u003e\n\nDon't bother pre-checking the bounds of the potential hugepage, i.e. don't\ncheck that e.g. sp-\u003egfn + KVM_PAGES_PER_HPAGE(sp-\u003erole.level + 1) is also\nwithin the memslot, as the checks performed by kvm_mmu_max_mapping_level()\nare a superset of the basic bounds checks.  I.e. pre-checking the full\nrange would be a dubious micro-optimization.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"KVM: x86/mmu: Ensure hugepage is in by slot before checking max mapping level","id":"CVE-2026-63807","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"memory_corruption","year":"2026"},"n_packages":0,"n_references":7,"next":{"headline":"exfat: fix potential use-after-free in exfat_find_dir_entry()","id":"CVE-2026-63808"},"packages":[],"prev":{"headline":"KVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned()","id":"CVE-2026-63806"},"products":["Linux"],"published":"2026-07-19","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-10-19","vendors":["Linux"]},"summary":"A guest VM can trigger an out-of-bounds memory access in the Linux kernel KVM module, causing a host crash or potential code execution.","url":"https://insights.sbomify.com/CVE-2026-63807/"}