{"api_version":"1","generated_at":"2026-11-01T09:41:13+00:00","cve":"CVE-2026-99177","urls":{"html":"https://cve.report/CVE-2026-99177","api":"https://cve.report/api/cve/CVE-2026-99177.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99177","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99177"},"summary":{"title":"KVM: SEV: Fix page dirtying in sev_gmem_post_populate()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Fix page dirtying in sev_gmem_post_populate()\n\nset_page_dirty() requires that the caller holds some kind of lock to\nensure that the page's mapping does not concurrently go away.\nThat is not the case for a random page we got from get_user_pages_fast(),\nso use set_page_dirty_lock().\n\n[sean: tag for stable]","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-28 11:17:38","updated_at":"2026-10-31 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the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Fix page dirtying in sev_gmem_post_populate()\n\nset_page_dirty() requires that the caller holds some kind of lock to\nensure that the page's mapping does not concurrently go away.\nThat is not the case for a random page we got from get_user_pages_fast(),\nso use set_page_dirty_lock().\n\n[sean: tag for stable]"}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - Local ioctl(KVM_MEMORY_ENCRYPT_OP) follows kvm_vm_ioctl() → sev_mem_enc_ioctl() → snp_launch_update() → kvm_gmem_populate() → patched sev_gmem_post_populate(); the triggering CPUID page comes from the ioctl's userspace uaddr, not a network peer or guest.\nAC:L - The caller can supply a CPUID page that makes SEV_CMD_SNP_LAUNCH_UPDATE return SEV_RET_INVALID_PARAM and concurrently tear down its file-backed source mapping; the same attacker controls both sides of the set_page_dirty() race.\nPR:L - kvm_vm_ioctl() requires a same-mm VM fd and __sev_issue_cmd() requires a valid /dev/sev fd, but sev_mem_enc_ioctl() and snp_launch_update() perform no capability check; an unprivileged VMM account granted those device fds suffices.\nUI:N - The attacker creates and initializes the SNP VM, submits the rejected CPUID page, and races teardown of that page's mapping without any action by another user.\nS:U - The UAF occurs in the host kernel while servicing the host VMM's launch ioctl; it is not a guest-to-host escape because the guest has not begun executing on this pre-launch failure path.\nC:H - folio_mark_dirty() can invoke mapping->a_ops->dirty_folio through a freed inode-embedded address_space; grooming the stale object and exploiting the resulting kernel control-flow or mapping-state corruption can provide arbitrary host-kernel memory access.\nI:H - For buffer-backed pages, the stale callback can enter block_dirty_folio(), modify freed mapping locks and buffer state, then call __folio_mark_dirty() and __mark_inode_dirty() through reused objects, providing exploitable UAF writes and potential kernel code execution.\nA:H - The stale dirty_folio callback can dereference freed or poisoned a_ops, spinlocks, buffer heads, or host-inode state, causing a host kernel oops or panic."}]}],"providerMetadata":{"dateUpdated":"2026-10-31T12:44:45.294Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/184382f9852d433af21de96c334ecf43b8414ed8"},{"url":"https://git.kernel.org/stable/c/97818b2fa7082e940ddd36dab12a68615300e798"}],"title":"KVM: SEV: Fix page dirtying in 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mapping does not concurrently go away.\nThat is not the case for a random page we got from get_user_pages_fast(),\nso use set_page_dirty_lock().\n\n[sean: tag for stable]","Type":"Description","Title":"KVM: SEV: Fix page dirtying in sev_gmem_post_populate()"}]}}}