{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2025-40026", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-40026", "idYear": 2025, "status": "PUBLISHED", "publishedAt": "2025-10-28T09:32:33.075Z", "updatedAt": "2026-10-15T22:02:36.361Z", "importedAt": "2026-10-24T01:57:34.152Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: Don't (re)check L1 intercepts when completing userspace I/O\n\nWhen completing emulation of instruction that generated a userspace exit\nfor I/O, don't recheck L1 intercepts as KVM has already finished that\nphase of instruction execution, i.e. has already committed to allowing L2\nto perform I/O. If L1 (or host userspace) modifies the I/O permission\nbitmaps during the exit to userspace, KVM will treat the access as being\nintercepted despite already having emulated the I/O access.\n\nPivot on EMULTYPE_NO_DECODE to detect that KVM is completing emulation.\nOf the three users of EMULTYPE_NO_DECODE, only complete_emulated_io() (the\nintended \"recipient\") can reach the code in question. gp_interception()'s\nuse is mutually exclusive with is_guest_mode(), and\ncomplete_emulated_insn_gp() unconditionally pairs EMULTYPE_NO_DECODE with\nEMULTYPE_SKIP.\n\nThe bad behavior was detected by a syzkaller program that toggles port I/O\ninterception during the userspace I/O exit, ultimately resulting in a WARN\non vcpu->arch.pio.count being non-zero due to KVM no completing emulation\nof the I/O instruction.\n\n WARNING: CPU: 23 PID: 1083 at arch/x86/kvm/x86.c:8039 emulator_pio_in_out+0x154/0x170 [kvm]\n Modules linked in: kvm_intel kvm irqbypass\n CPU: 23 UID: 1000 PID: 1083 Comm: repro Not tainted 6.16.0-rc5-c1610d2d66b1-next-vm #74 NONE\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n RIP: 0010:emulator_pio_in_out+0x154/0x170 [kvm]\n PKRU: 55555554\n Call Trace:\n \n kvm_fast_pio+0xd6/0x1d0 [kvm]\n vmx_handle_exit+0x149/0x610 [kvm_intel]\n kvm_arch_vcpu_ioctl_run+0xda8/0x1ac0 [kvm]\n kvm_vcpu_ioctl+0x244/0x8c0 [kvm]\n __x64_sys_ioctl+0x8a/0xd0\n do_syscall_64+0x5d/0xc60\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n ", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9", "status": "affected", "versionType": "git", "lessThan": "a908eca437789589dd4624da428614c1275064dc" }, { "version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9", "status": "affected", "versionType": "git", "lessThan": "00338255bb1f422642fb2798ebe92e93b6e4209b" }, { "version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9", "status": "affected", "versionType": "git", "lessThan": "e0ce3ed1048a47986d15aef1a98ebda25560d257" }, { "version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9", "status": "affected", "versionType": "git", "lessThan": "ba35a5d775799ce5ad60230be97336f2fefd518e" }, { "version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9", "status": "affected", "versionType": "git", "lessThan": "3d3abf3f7e8b1abb082070a343de82d7efc80523" }, { "version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9", "status": "affected", "versionType": "git", "lessThan": "e7177c7e32cb806f348387b7f4faafd4a5b32054" }, { "version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9", "status": "affected", "versionType": "git", "lessThan": "3a062a5c55adc5507600b9ae6d911e247e2f1d6e" }, { "version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9", "status": "affected", "versionType": "git", "lessThan": "7366830642505683bbe905a2ba5d18d6e4b512b8" }, { "version": "8a76d7f25f8f24fc5a328c8e15e4a7313cf141b9", "status": "affected", "versionType": "git", "lessThan": "e750f85391286a4c8100275516973324b621a269" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "3.0", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "3.0" }, { "version": "5.4.301", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.4.*" }, { "version": "5.10.246", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.195", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.157", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.111", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.52", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.16.12", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.16.*" }, { "version": "6.17.2", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.17.*" }, { "version": "6.18", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }